Reference signal transmission method and transmission apparatus

ABSTRACT

This application provides a reference signal communication method and communication apparatus. The method includes determining a resource block offset of a frequency domain position of a phase tracking reference signal (PTRS) based on a frequency domain density of the PTRS, an identifier of a terminal device, and a first bandwidth, in accordance with a ratio of the first bandwidth to the frequency domain density of the PTRS being a non-integer. The first bandwidth is a bandwidth scheduled by a network device for the terminal device. The method further includes sending or receiving the PTRS based on the resource block offset of the frequency domain position of the PTRS.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/442,129, filed on Jun. 14, 2019, which is a continuation ofInternational Application No. PCT/CN2018/105765, filed on Sep. 14, 2018which claims priority to Chinese Patent Application No. 201711148135.2,filed on Nov. 17, 2017. All of the afore-mentioned patent applicationsare hereby incorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the communications field, and morespecifically, to a reference signal transmission method and transmissionapparatus in the communications field.

BACKGROUND

As a network system develops, requirements for a communication rate anda communication capacity gradually increase, and a requirement forhigh-frequency resources increases accordingly. However, a frequencyincrease is accompanied with an increase of phase noise generated byrandom jitter of a frequency component, namely, a local oscillator.Therefore, impact of the phase noise cannot be ignored in high-frequencywireless communication. Generally, a transmit end device may send aphase tracking reference signal (PTRS) that is known in advance, and areceive end may estimate phase noise based on the received PTRS.

When a plurality of terminal devices use a same PTRS sequence in onecell or sector, PTRS frequency domain positions to which the pluralityof terminal devices perform mapping by using a same PTRS port are thesame. In this case, different PTRSs mapped to a same frequency domainposition interfere with each other, thereby affecting phase noiseestimation. Therefore, how to randomize PTRS interference becomes anurgent problem to be resolved.

SUMMARY

This application provides a reference signal transmission method andtransmission apparatus, to help randomize PTRS interference.

According to a first aspect, this application provides a referencesignal transmission method, and the method includes: determining, by anetwork device, a resource block offset of a frequency domain positionof a phase tracking reference signal (PTRS) of a terminal device basedon PTRS information of the terminal device, an identifier of theterminal device, and first bandwidth, where the PTRS informationincludes a frequency domain density or a frequency domain interval ofthe PTRS, and the first bandwidth is bandwidth scheduled by the networkdevice for the terminal device; and performing, by the network device,transmission of the PTRS with the terminal device based on the resourceblock offset of the frequency domain position of the PTRS.

According to the reference signal transmission method provided in thisembodiment of this application, the resource block offset of thefrequency domain position of the PTRS of the terminal device isdetermined by using information related to the terminal device, to helprandomize PTRS interference, thereby stabilizing performance ofPTRS-based phase noise estimation.

It should be understood that the network device may estimate phase noisebased on a PTRS, or may estimate phase noise based on a phasecompensation reference signal (PCRS). For consistency of description,the PTRS and the PCRS are collectively referred to as a PTRS in thisembodiment of this application, and this is not limited in thisembodiment of this application.

It should be further understood that a frequency domain density (afrequency domain interval) n of a PTRS may mean that a PTRS symbol ismapped to one in every n resource blocks (RB). A value of n may be, forexample, 1, 2, 4, 8, or 16.

It should be further understood that the PTRS information in thisembodiment of this application includes the frequency domain density orthe frequency domain interval. For ease of description, in thisembodiment of this application, only the frequency domain density isused as an example to describe the PTRS information. However, a case inwhich the PTRS information is the frequency domain interval also fallswithin protection of this embodiment of this application.

Optionally, before determining the resource block offset of thefrequency domain position of the PTRS of the terminal device based onthe PTRS information of the terminal device, the identifier of theterminal device, and the first bandwidth, the network device may obtainthe PTRS information, the identifier of the terminal device, and thefirst bandwidth.

Optionally, the network device may obtain the identifier of the terminaldevice in a plurality of manners, and this is not limited in thisembodiment of this application.

In an optional embodiment, when requesting to access a network of thenetwork device, the terminal device may send an access request to thenetwork device. The access request carries the identifier of theterminal device. The network device may receive the access request sentby the terminal device, and obtain the identifier of the terminal devicefrom the access request.

In another optional embodiment, when requesting scheduling informationfrom the network device, the terminal device may send a schedulingrequest to the network device. The scheduling request carries theidentifier of the terminal device. The network device may receive thescheduling request from the terminal device, and obtain the identifierof the terminal device from the scheduling request.

Optionally, the identifier of the terminal device may include, forexample, at least one of the following identifiers: a cell radio networktemporary identifier (C-RNTI), a random access radio network temporaryidentifier (RA-RNTI), a temporary C-RNTI, and a transmit power controlradio network temporary identifier (TPC-RNTI), and this is not limitedin this embodiment of this application.

Optionally, the network device may obtain the first bandwidth in aplurality of manners, and this is not limited in this embodiment of thisapplication.

In an optional embodiment, the network device may configure the firstbandwidth for the terminal device.

Optionally, the network device may obtain the PTRS information of theterminal device in a plurality of manners, and this is not limited inthis embodiment of this application.

In an optional embodiment, the network device may configure the PTRSinformation for the terminal device.

In another optional embodiment, the network device may determine thePTRS information of the terminal device based on the first bandwidth anda first mapping relationship. The first mapping relationship is used toindicate a correspondence between the first bandwidth and the PTRSinformation.

Optionally, the network device and the terminal device may pre-agree onthe first mapping relationship, or the network device may configure thefirst mapping relationship for the terminal device by using higher layersignaling.

Optionally, the network device may determine the resource block offsetof the frequency domain position of the PTRS based on at least one ofthe PTRS information, the identifier of the terminal device, and thefirst bandwidth, and this is not limited in this embodiment of thisapplication.

In an optional embodiment, the network device may determine the resourceblock offset of the frequency domain position of the PTRS based on thePTRS information and the identifier of the terminal device.

In another optional embodiment, the network device may determine theresource block offset of the frequency domain position of the PTRS basedon the PTRS information, the identifier of the terminal device, and thefirst bandwidth.

In a possible implementation, the determining, by a network device, aresource block offset of a frequency domain position of a PTRS of aterminal device based on PTRS information of the terminal device, anidentifier of the terminal device, and first bandwidth includes: when aratio of the first bandwidth to the frequency domain density of the PTRSis less than or equal to a first preset value, or a ratio of the firstbandwidth to the frequency domain interval of the PTRS is less than orequal to the first preset value, determining, by the network device, theresource block offset of the frequency domain position of the PTRS basedon the PTRS information of the terminal device, the identifier of theterminal device, and the first bandwidth.

Optionally, that the network device determines the resource block offsetbased on the PTRS information, the identifier of the terminal device,and the first bandwidth may be that when a second condition issatisfied, the network device may determine the resource block offsetbased on the PTRS information, the identifier of the terminal device,and the first bandwidth.

Optionally, the second condition may be at least one of the followingconditions:

(1) The ratio of the first bandwidth to the frequency domain density ofthe PTRS is less than or equal to a first threshold.

(2) The ratio of the first bandwidth to the frequency domain density ofthe PTRS is a non-integer.

(3) A maximum quantity of PTRSs that can be mapped under the conditionsof the PTRS information and the first bandwidth is less than or equal toa third threshold.

(4) A minimum quantity of PTRSs that can be mapped under the conditionsof the PTRS information and the first bandwidth is less than or equal toa fourth threshold.

(5) A ratio of the minimum quantity of PTRSs to the maximum quantity ofPTRSs is less than or equal to a second threshold.

(6) The first bandwidth is less than or equal to a fifth threshold.

Optionally, one or more of the first threshold to the fifth thresholdmay be pre-agreed on by the network device and the terminal device, ormay be configured by the network device for the terminal device by usingfirst signaling, and this is not limited in this embodiment of thisapplication.

Optionally, the first signaling may be radio resource control (RRC)signaling, Media Access Control (MAC) control element (CE) signaling, ordownlink control information (DCI) signaling, and this is not limited inthis embodiment of this application.

Optionally, the resource block offset of the frequency domain positionof the PTRS may mean that an offset of the frequency domain position ofthe PTRS is measured in RBs, in other words, the offset of the frequencydomain position of the PTRS is an RB-level offset.

It should be understood that the resource block offset of the frequencydomain position of the PTRS may be understood as a resource block offsetof a frequency domain position of the PTRS in a relative RB.

It should be further understood that the frequency domain position ofthe PTRS may be understood as a frequency domain position to which aPTRS symbol in a sequence of the PTRS is mapped.

It should be further understood that a quantity of PTRSs in thisembodiment of this application may be understood as a quantity of PTRSsymbols.

It should be further understood that when the network device allocates Kphysical resource blocks (PRB) to the terminal device, relative RBswhose sequence numbers (or numbers or indexes) are 0, 1, . . . , and K−1may be obtained in ascending order of sequence numbers of the K PRBs,where K is an integer greater than 0. For example, the network deviceallocates four PRBs whose sequence numbers are 0, 1, 6, and 7 to theterminal device, and four relative RBs whose sequence numbers are 0, 1,2, and 3 are obtained in ascending order of sequence numbers.

Optionally, the K physical resource blocks may be contiguous ornoncontiguous, and this is not limited in this embodiment of thisapplication.

It should be further understood that a frequency domain density N of aPTRS may mean that a frequency domain interval of the PTRS is N relativeRBs. In this case, a PTRS symbol 0 in a sequence of the PTRS correspondsto one of the relative RBs 0 to N−1, a PTRS symbol 1 corresponds to oneof the relative RBs N to 2*N−1, and so on, to obtain a relative RBcorresponding to each PTRS symbol in the sequence of the PTRS.

Specifically, a frequency domain position of a PTRS symbol M in thesequence of the PTRS in a relative RB may be a relative RB Δf+M*N, whereΔf indicates the resource block offset of the frequency domain position,N indicates the frequency domain density of the PTRS, and M is aninteger greater than or equal to 0.

In a possible implementation, the determining, by a network device, aresource block offset of a frequency domain position of a PTRS of aterminal device based on PTRS information of the terminal device, anidentifier of the terminal device, and first bandwidth includes:performing, by the network device, modulo processing on the firstbandwidth based on the PTRS information, to obtain second bandwidth; anddetermining, by the network device, the resource block offset of thefrequency domain position of the PTRS based on the second bandwidth andthe identifier of the terminal device.

It should be understood that during determining of the resource blockoffset of the PTRS of the terminal device based on the identifier of theterminal device, the identifier of the terminal device may be mapped tothe resource block offset of the PTRS by using a modulo method, and whenthe ratio of the bandwidth (the first bandwidth) scheduled by thenetwork device for the terminal device to the frequency domain densityof the PTRS is relatively small, a bandwidth remainder (the secondbandwidth) may replace the original frequency domain density in a moduloformula for mapping the identifier of the terminal device to theresource block offset of the PTRS. A modular operation is provided tomap a UE-ID to a RB-level offset. If a ratio of a scheduled bandwidth(BW) to the PTRS frequency density is small, the modular BW will replacethe frequency density in the modular to map the UE-ID to the RB-leveloffset.

According to the reference signal transmission method provided in thisembodiment of this application, the network device determines theresource block offset of the frequency domain position of the PTRS basedon the second bandwidth and the identifier of the terminal device, sothat a quantity of PTRSs mapped in the first bandwidth is the same as aquantity of PTRSs mapped when a frequency domain offset is 0. In thisway, the following problem can be avoided: when the frequency domainoffset is relatively large, the quantity of PTRSs mapped in the firstbandwidth significantly decreases or is 0, and therefore the PTRS cannotbe transmitted between the terminal device and the network device in thefirst bandwidth, and phase noise cannot be estimated based on the PTRS.

In a possible implementation, the transmission method further includes:when the ratio of the first bandwidth to the frequency domain density ofthe PTRS is greater than a second preset value, or the ratio of thefirst bandwidth to the frequency domain interval of the PTRS is greaterthan the second preset value, determining, by the network device, theresource block offset of the frequency domain position of the PTRS basedon the PTRS information and the identifier of the terminal device.

It should be understood that the second preset value may be the same asthe first preset value.

Optionally, that the network device determines the resource block offsetof the frequency domain position of the PTRS based on the PTRSinformation and the identifier of the terminal device may be that when afirst condition is satisfied, the network device determines the resourceblock offset of the frequency domain position of the PTRS based on thePTRS information and the identifier of the terminal device.

Optionally, the first condition may be at least one of the followingconditions:

(1) The ratio of the first bandwidth to the frequency domain density ofthe PTRS is greater than a first threshold.

(2) The ratio of the first bandwidth to the frequency domain density ofthe PTRS is an integer.

(3) A maximum quantity of PTRSs that can be mapped under the conditionsof the PTRS information and the first bandwidth is greater than a thirdthreshold.

(4) A minimum quantity of PTRSs that can be mapped under the conditionsof the PTRS information and the first bandwidth is greater than a fourththreshold.

(5) A ratio of the minimum quantity of PTRSs to the maximum quantity ofPTRSs is greater than a second threshold.

(6) The first bandwidth is greater than a fifth threshold.

Optionally, one or more of the first threshold to the fifth thresholdmay be pre-agreed on by the network device and the terminal device, ormay be configured by the network device for the terminal device by usingfirst signaling, and this is not limited in this embodiment of thisapplication.

Optionally, the first signaling may be RRC signaling, MAC CE signaling,or DCI signaling, and this is not limited in this embodiment of thisapplication.

According to a second aspect, this application provides a referencesignal transmission method, and the method includes: determining, by aterminal device, a resource block offset of a frequency domain positionof a phase tracking reference signal (PTRS) based on PTRS information,an identifier of the terminal device, and first bandwidth, where thePTRS information includes a frequency domain density or a frequencydomain interval of the PTRS, and the first bandwidth is bandwidthscheduled by a network device for the terminal device; and performing,by the terminal device, transmission of the PTRS with the network devicebased on the resource block offset of the frequency domain position ofthe PTRS.

According to the reference signal transmission method provided in thisembodiment of this application, the resource block offset of thefrequency domain position of the PTRS of the terminal device isdetermined by using information related to the terminal device, to helprandomize PTRS interference, thereby stabilizing performance ofPTRS-based phase noise estimation.

Optionally, before determining the resource block offset of thefrequency domain position of the PTRS based on the PTRS information, theidentifier of the terminal device, and the first bandwidth, the terminaldevice may obtain the PTRS information, the identifier of the terminaldevice, and the first bandwidth.

Optionally, the identifier of the terminal device may include, forexample, at least one of the following identifiers: a cell radio networktemporary identifier (C-RNTI), a random access radio network temporaryidentifier (RA-RNTI), a temporary C-RNTI, and a transmit power controlradio network temporary identifier (TPC-RNTI), and this is not limitedin this embodiment of this application.

Optionally, the terminal device may generate the identifier.

Optionally, the terminal device may obtain the first bandwidth in aplurality of manners, and this is not limited in this embodiment of thisapplication.

In an optional embodiment, the terminal device may receive firstconfiguration information sent by the network device, and obtain thefirst bandwidth from the first configuration information.

Optionally, the terminal device may obtain the PTRS information of theterminal device in a plurality of manners, and this is not limited inthis embodiment of this application.

In an optional embodiment, the terminal device may receive secondconfiguration information sent by the network device, and obtain thePTRS information from the second configuration information.

In another optional embodiment, the terminal device may receive firstconfiguration information sent by the network device, obtain the firstbandwidth from the first configuration information, and determine thePTRS information of the terminal device based on the first bandwidth anda first mapping relationship. The first mapping relationship is used toindicate a correspondence between the first bandwidth and the PTRSinformation.

Optionally, the network device and the terminal device may pre-agree onthe first mapping relationship, or the network device may configure thefirst mapping relationship for the terminal device by using higher layersignaling.

In a possible implementation, the determining, by a terminal device, aresource block offset of a frequency domain position of a PTRS based onPTRS information, an identifier of the terminal device, and firstbandwidth includes: when a ratio of the first bandwidth to the frequencydomain density of the PTRS is less than or equal to a first presetvalue, or a ratio of the first bandwidth to the frequency domaininterval of the PTRS is less than or equal to the first preset value,determining, by the terminal device, the resource block offset of thefrequency domain position of the PTRS based on the PTRS information, theidentifier of the terminal device, and the first bandwidth.

In a possible implementation, the determining, by a terminal device, aresource block offset of a frequency domain position of a PTRS based onPTRS information, an identifier of the terminal device, and firstbandwidth includes: performing, by the terminal device, moduloprocessing on the first bandwidth based on the PTRS information, toobtain second bandwidth; and determining, by the terminal device, theresource block offset of the frequency domain position of the PTRS basedon the second bandwidth and the identifier of the terminal device.

In a possible implementation, the transmission method further includes:when the ratio of the first bandwidth to the frequency domain density ofthe PTRS is greater than a second preset value, or the ratio of thefirst bandwidth to the frequency domain interval of the PTRS is greaterthan the second preset value, determining, by the terminal device, theresource block offset of the frequency domain position of the PTRS basedon the PTRS information and the identifier of the terminal device.

According to a third aspect, this application provides a referencesignal transmission method, and the method includes: determining, by anetwork device, a second frequency domain offset based on a firstfrequency domain offset and at least one subcarrier to which ademodulation reference signal (DMRS) of a terminal device is to bemapped in a first resource block, where the first resource block is aresource block to which a first PTRS of the terminal device is to bemapped, the first frequency domain offset is used to determine, from thefirst resource block, a frequency domain position of a resource elementto which the first PTRS is to be mapped, and the second frequency domainoffset is used to determine, from the at least one subcarrier, afrequency domain position to which the first PTRS is to be mapped;determining, by the network device based on a frequency domain positionof the at least one subcarrier and the second frequency domain offset,the frequency domain position to which the first PTRS is to be mapped;and performing, by the network device, transmission of the first PTRSwith the terminal device based on the frequency domain position to whichthe first PTRS is to be mapped.

According to the reference signal transmission method provided in thisembodiment of this application, the frequency domain position to whichthe first PTRS is to be mapped can be determined, based on the secondfrequency domain offset, from a subcarrier set occupied by a DMRS portassociated with the first PTRS.

It should be understood that a relative offset (the second frequencydomain offset) in a subcarrier set may be defined, and is used toindicate a subcarrier to which a PTRS is to be mapped in a givenresource block (the first resource block). The subcarrier set includes asubcarrier occupied by a DMRS port associated with the PTRS, andincludes no direct current subcarrier. A relative offset among thesubcarrier set only includes the subcarrier occupied by the associatedDMRS port, and does not include the direct current (DC) tone.

According to the reference signal transmission method provided in thisembodiment of this application, because a DC subcarrier is removed fromthe subcarrier set occupied by the DMRS port associated with the firstPTRS, the following problem can be avoided: the first PTRS is mapped toa frequency domain position on which the DC subcarrier is located, whichcauses a conflict between the PTRS and the DC subcarrier.

In a possible implementation, when both the frequency domain position towhich the first PTRS is to be mapped and a frequency domain position towhich a second PTRS of the terminal device is to be mapped are a firstsubcarrier in the at least one subcarrier, the performing, by thenetwork device, transmission of the first PTRS with the terminal devicebased on the frequency domain position to which the first PTRS is to bemapped includes: determining, by the network device, a second subcarrierbased on the first subcarrier, where the second subcarrier is asubcarrier spaced from the first subcarrier by a minimum quantity ofsubcarriers in the at least one subcarrier; and performing, by thenetwork device, transmission of the first PTRS with the terminal deviceon the second subcarrier.

According to the reference signal transmission method provided in thisembodiment of this application, when a frequency domain position of aresource element to which the first PTRS is to be mapped is the same asa frequency domain position of a resource element to which the secondPTRS is to be mapped, the frequency domain position of the resourceelement to which the first PTRS is to be mapped or the frequency domainposition of the resource element to which the second PTRS is to bemapped may be adjusted, so that the first PTRS and the second PTRS aremapped to two different subcarriers in the subcarrier set occupied bythe DMRS port, and the two subcarriers have adjacent numbers or indexesin the subcarrier set, thereby avoiding mutual interference between thefirst PTRS and the second PTRS.

In a possible implementation, before the determining, by a networkdevice, a second frequency domain offset based on a first frequencydomain offset and at least one subcarrier to which a DMRS of a terminaldevice is to be mapped in a first resource block, the method furtherincludes: obtaining, by the network device, reference information of theterminal device, where the reference information includes at least oneof an identifier of the terminal device and scheduling information ofthe terminal device; and determining, by the network device, the firstfrequency domain offset based on the reference information of theterminal device.

In a possible implementation, the scheduling information of the terminaldevice includes at least one of the following information: schedulinginformation of the DMRS, scheduling information of the first PTRS,scheduling information of a sounding reference signal (SRS), andscheduling information of a codeword.

Optionally, the scheduling information of the DMRS may include at leastone of a port number, a port quantity, a port pattern, a resourceelement mapping, a sequence scrambling index/number, and a subcarriersequence number/resource element of the DMRS. The scheduling informationof the first PTRS may include at least one of a port number, a portquantity, a frequency domain density, a resource element mapping, and asequence scrambling index/number of the first PTRS. The schedulinginformation of the SRS may include at least one of a port number, a portquantity, a port pattern, a resource element mapping, a sequencescrambling index/number, and a subcarrier sequence number/resourceelement of the SRS. The scheduling information of the codeword mayinclude a codeword number and/or a codeword quantity of the codeword.

According to a fourth aspect, this application provides a referencesignal transmission method, and the method includes: determining, by aterminal device, a second frequency domain offset based on a firstfrequency domain offset and at least one subcarrier to which ademodulation reference signal (DMRS) of the terminal device is to bemapped in a first resource block, where the first resource block is aresource block to which a first phase tracking reference signal (PTRS)is to be mapped, the first frequency domain offset is used to determine,from the first resource block, a frequency domain position of a resourceelement to which the first PTRS is to be mapped, and the secondfrequency domain offset is used to determine, from the at least onesubcarrier, a frequency domain position to which the first PTRS is to bemapped; determining, by the terminal device based on a frequency domainposition of the at least one subcarrier and the second frequency domainoffset, the frequency domain position to which the first PTRS is to bemapped; and performing, by the terminal device, transmission of thefirst PTRS with a network device based on the frequency domain positionto which the first PTRS is to be mapped.

According to the reference signal transmission method provided in thisembodiment of this application, the frequency domain position to whichthe first PTRS is to be mapped can be determined, based on the secondfrequency domain offset, from a subcarrier set occupied by a DMRS portassociated with the first PTRS.

In a possible implementation, the at least one subcarrier includes nodirect current subcarrier.

In a possible implementation, when both the frequency domain position towhich the first PTRS is to be mapped and a frequency domain position towhich a second PTRS of the terminal device is to be mapped are a firstsubcarrier in the at least one subcarrier, the performing, by theterminal device, transmission of the first PTRS with a network devicebased on the frequency domain position to which the first PTRS is to bemapped includes: determining, by the terminal device, a secondsubcarrier based on the first subcarrier, where the second subcarrier isa subcarrier spaced from the first subcarrier by a minimum quantity ofsubcarriers in the at least one subcarrier; and performing, by theterminal device, transmission of the first PTRS with the network deviceon the second subcarrier.

In a possible implementation, before the determining, by a terminaldevice, a second frequency domain offset based on a first frequencydomain offset and at least one subcarrier to which a DMRS of theterminal device is to be mapped in a first resource block, the methodfurther includes: obtaining, by the terminal device, referenceinformation of the terminal device, where the reference informationincludes at least one of an identifier of the terminal device andscheduling information of the terminal device; and determining, by theterminal device, the first frequency domain offset based on thereference information of the terminal device.

In a possible implementation, the scheduling information of the terminaldevice includes at least one of the following information: schedulinginformation of the DMRS, scheduling information of the first PTRS,scheduling information of a sounding reference signal (SRS), andscheduling information of a codeword.

According to a fifth aspect, this application provides a referencesignal transmission apparatus, configured to perform the transmissionmethod according to any one of the first aspect and the possibleimplementations of the first aspect.

According to a sixth aspect, this application provides a referencesignal transmission apparatus, configured to perform the transmissionmethod according to any one of the second aspect and the possibleimplementations of the second aspect.

According to a seventh aspect, this application provides a referencesignal transmission apparatus, configured to perform the transmissionmethod according to any one of the third aspect and the possibleimplementations of the third aspect.

According to an eighth aspect, this application provides a referencesignal transmission apparatus, configured to perform the transmissionmethod according to any one of the fourth aspect and the possibleimplementations of the third aspect.

According to a ninth aspect, this application provides a referencesignal transmission apparatus, the transmission apparatus includes amemory, a processor, a transceiver, and a computer program that isstored in the memory and that may run on the processor, and whenexecuting the computer program, the processor performs the transmissionmethod according to any one of the first aspect and the possibleimplementations of the first aspect.

According to a tenth aspect, this application provides a referencesignal transmission apparatus, the transmission apparatus includes amemory, a processor, a transceiver, and a computer program that isstored in the memory and that may run on the processor, and whenexecuting the computer program, the processor performs the transmissionmethod according to any one of the second aspect and the possibleimplementations of the second aspect.

According to an eleventh aspect, this application provides a referencesignal transmission apparatus, the transmission apparatus includes amemory, a processor, a transceiver, and a computer program that isstored in the memory and that may run on the processor, and whenexecuting the computer program, the processor performs the transmissionmethod according to any one of the third aspect and the possibleimplementations of the third aspect.

According to a twelfth aspect, this application provides a referencesignal transmission apparatus, the transmission apparatus includes amemory, a processor, a transceiver, and a computer program that isstored in the memory and that may run on the processor, and whenexecuting the computer program, the processor performs the transmissionmethod according to any one of the fourth aspect and the possibleimplementations of the fourth aspect.

According to a thirteenth aspect, this application provides a computerreadable medium, configured to store a computer program, where thecomputer program includes an instruction used to perform thetransmission method according to any one of the first aspect and thepossible implementations of the first aspect.

According to a fourteenth aspect, this application provides a computerreadable medium, configured to store a computer program, where thecomputer program includes an instruction used to perform thetransmission method according to any one of the second aspect and thepossible implementations of the second aspect.

According to a fifteenth aspect, this application provides a computerreadable medium, configured to store a computer program, where thecomputer program includes an instruction used to perform thetransmission method according to any one of the third aspect and thepossible implementations of the third aspect.

According to a sixteenth aspect, this application provides a computerreadable medium, configured to store a computer program, where thecomputer program includes an instruction used to perform thetransmission method according to any one of the fourth aspect and thepossible implementations of the fourth aspect.

According to a seventeenth aspect, this application provides a computerprogram product including an instruction, where when the computerprogram product runs on a computer, the computer performs thetransmission method according to any one of the first aspect and thepossible implementations of the first aspect.

According to an eighteenth aspect, this application provides a computerprogram product including an instruction, where when the computerprogram product runs on a computer, the computer performs thetransmission method according to any one of the second aspect and thepossible implementations of the second aspect.

According to a nineteenth aspect, this application provides a computerprogram product including an instruction, where when the computerprogram product runs on a computer, the computer performs thetransmission method according to any one of the third aspect and thepossible implementations of the third aspect.

According to a twentieth aspect, this application provides a computerprogram product including an instruction, where when the computerprogram product runs on a computer, the computer performs thetransmission method according to any one of the fourth aspect and thepossible implementations of the fourth aspect.

According to a twenty-first aspect, this application provides acommunications chip, where an instruction is stored in thecommunications chip, and when the instruction runs on a network deviceor a terminal device, the network device or the terminal device performsthe method according to the foregoing aspects.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic block diagram of a communications system accordingto an embodiment of this application;

FIG. 2 is a schematic diagram of a frequency domain position to which aPTRS is mapped in the prior art;

FIG. 3 is a schematic flowchart of a reference signal transmissionmethod according to an embodiment of this application;

FIG. 4 is a schematic diagram of a relationship between a frequencydomain position of a relative RB to which a PTRS is to be mapped and afrequency domain position of a PRB to which the PTRS is to be mappedaccording to an embodiment of this application;

FIG. 5 is a schematic flowchart of another reference signal transmissionmethod according to an embodiment of this application;

FIG. 6 is a schematic diagram of a frequency domain position of asubcarrier to which a DMRS is to be mapped according to an embodiment ofthis application;

FIG. 7 is a schematic block diagram of a reference signal transmissionapparatus according to an embodiment of this application;

FIG. 8 is a schematic block diagram of another reference signaltransmission apparatus according to an embodiment of this application;

FIG. 9 is a schematic block diagram of still another reference signaltransmission apparatus according to an embodiment of this application;

FIG. 10 is a schematic block diagram of yet another reference signaltransmission apparatus according to an embodiment of this application;

FIG. 11 is a schematic block diagram of yet another reference signaltransmission apparatus according to an embodiment of this application;

FIG. 12 is a schematic block diagram of yet another reference signaltransmission apparatus according to an embodiment of this application;

FIG. 13 is a schematic block diagram of yet another reference signaltransmission apparatus according to an embodiment of this application;and

FIG. 14 is a schematic block diagram of yet another reference signaltransmission apparatus according to an embodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following describes the technical solutions in this application withreference to the accompanying drawings.

It should be understood that the technical solutions in embodiments ofthis application may be applied to various communications systems, suchas a Global System for Mobile Communications (GSM), a Code DivisionMultiple Access (CDMA) system, a Wideband Code Division Multiple Access(WCDMA) system, a general packet radio service (GPRS) system, a LongTerm Evolution (LTE) system, an LTE frequency division duplex (FDD)system, an LTE time division duplex (TDD) system, a Universal MobileTelecommunications System (UMTS), a Worldwide Interoperability forMicrowave Access (WiMAX) communications system, a wireless local areanetwork (WLAN), or a future fifth generation (5G) wirelesscommunications system.

FIG. 1 is a schematic architectural diagram of a communications system100 according to an embodiment of this application. As shown in FIG. 1,the communications system 100 may include at least one network device (anetwork device 110 shown in FIG. 1) and a plurality of terminal devices(a terminal device 120 and a terminal device 130 shown in FIG. 1), andthe at least one network device and the plurality of terminal devicesmay perform wireless communication with each other.

Optionally, the network device may provide communication coverage for aspecific geographic area, and may communicate with a UE that fallswithin the coverage. The network device may be: a base transceiverstation (BTS) in a GSM system or a CDMA system, a NodeB (NB) in a WCDMAsystem, an evolved NodeB (eNB or eNodeB) in an LTE system, or a radiocontroller in a cloud radio access network (CRAN). Alternatively, thenetwork device may be: a network device in a core network, a relaystation, an access point, a vehicular device, a wearable device, anetwork device in a future 5G network, an NR network, or a futureevolved public land mobile network (PLMN), or the like.

Optionally, the terminal device may be mobile or fixed. The terminaldevice may be an access terminal, a user equipment (UE), a subscriberunit, a subscriber station, a mobile station, a mobile console, a remotestation, a remote terminal, a mobile device, a user terminal, aterminal, a wireless communications device, a user agent, a userapparatus, or the like. The access terminal may be: a cellular phone, acordless phone, a Session Initiation Protocol (SIP) phone, a wirelesslocal loop (WLL) station, a personal digital assistant (PDA), a handhelddevice having a wireless communication function, a computing device,another processing device connected to a wireless modem, a vehiculardevice, a wearable device, a terminal device in a future 5G network, anNR network, or a future evolved PLMN, or the like.

FIG. 1 shows one network device and two terminal devices as an example.Optionally, the communications system 100 may further include aplurality of network devices, and coverage of each network device mayinclude another quantity of terminal devices. This is not limited inthis embodiment of this application. Optionally, the communicationssystem 100 may further include other network entities such as a networkcontroller and a mobility management entity, and this is not limited inthis embodiment of this application.

It should be understood that the network device or the terminal devicemay estimate phase noise based on a PTRS, or may estimate phase noisebased on a phase compensation reference signal (PCRS). For consistencyof description, the PTRS and the PCRS are collectively referred to as aPTRS in this embodiment of this application, and this is not limited inthis embodiment of this application.

It should be understood that a frequency domain density (a frequencydomain interval) n of a PTRS may mean that a PTRS symbol is mapped toone in every n resource blocks (RB). A value of n may be, for example,1, 2, 4, 8, or 16.

It should be further understood that PTRS information in this embodimentof this application includes the frequency domain density or thefrequency domain interval. For ease of description, in this embodimentof this application, only the frequency domain density is used as anexample to describe the PTRS information. However, a case in which thePTRS information is the frequency domain interval also falls withinprotection of this embodiment of this application.

In the prior art, a network device and a terminal device may transmit aPTRS by using a port 60 and/or a port 61. An offset that is of afrequency domain position of a PTRS and that is corresponding to theport 60 is 23 subcarriers, and an offset that is of the frequency domainposition of the PTRS and that is corresponding to the port 61 is 24subcarriers.

For example, as shown in FIG. 2, a frequency domain interval of a PTRSis 4 RBs (48 subcarriers) when a frequency domain density of the PTRS is4 and each RB includes 12 subcarriers. In this case, when the networkdevice and the terminal device transmit a PTRS by using the port 60, thePTRS is successively mapped to subcarriers whose sequence numbers are23, 23+1*48, 23+2*48, . . . , and 23+m*48; when the network device andthe terminal device transmit a PTRS by using the port 61, the PTRS issuccessively mapped to subcarriers whose sequence numbers are 24,24+1*48, 24+2*48, . . . , and 24+m*48, where m is an integer greaterthan or equal to 0.

In the prior art, when PTRS sequences of a first terminal device and asecond terminal device in one cell/sector are the same, and both thefirst terminal device and the second terminal device transmit a PTRS byusing a same port, a frequency domain position to which a PTRS of thefirst terminal device is mapped coincides with a frequency domainposition to which a PTRS of the second terminal device is mapped. Inthis case, PTRS signals received by the first terminal device and thesecond terminal device on a same subcarrier interfere with each other.Therefore, performance of PTRS-based phase noise estimation is unstable,and PTRS interference needs to be randomized to stabilize performance ofphase noise estimation that is based on a PTRS of each terminal device.

According to a reference signal transmission method provided in theembodiments of this application, a network device determines a resourceblock offset of a frequency domain position of a PTRS based on PTRSinformation of a terminal device, an identifier of the terminal device,and first bandwidth, where the PTRS information includes a frequencydomain density or a frequency domain interval of the PTRS, and the firstbandwidth is bandwidth scheduled by the network device for the terminaldevice; and the network device performs transmission of the PTRS withthe terminal device based on the resource block offset of the frequencydomain position of the PTRS. According to the reference signaltransmission method provided in the embodiments of this application, theresource block offset of the frequency domain position of the PTRS ofthe terminal device is determined by using information related to theterminal device, to help randomize PTRS interference, therebystabilizing performance of PTRS-based phase noise estimation.

FIG. 3 is a schematic flowchart of a reference signal transmissionmethod 300 according to an embodiment of this application. Thetransmission method 300 may be applied to the communications system 100shown in FIG. 1.

S310. During S310, a network device determines a resource block offsetof a frequency domain position of a PTRS of a terminal device based onPTRS information of the terminal device, an identifier of the terminaldevice, and first bandwidth, where the PTRS information includes afrequency domain density or a frequency domain interval of the PTRS, andthe first bandwidth is bandwidth scheduled by the network device for theterminal device.

Optionally, before S310, the network device may obtain the PTRSinformation, the identifier of the terminal device, and the firstbandwidth.

Optionally, the network device may obtain the identifier of the terminaldevice in a plurality of manners, and this is not limited in thisembodiment of this application.

In an optional embodiment, when requesting to access a network of thenetwork device, the terminal device may send an access request to thenetwork device. The access request carries the identifier of theterminal device. The network device may receive the access request sentby the terminal device, and obtain the identifier of the terminal devicefrom the access request.

In another optional embodiment, when requesting scheduling informationfrom the network device, the terminal device may send a schedulingrequest to the network device. The scheduling request carries theidentifier of the terminal device. The network device may receive thescheduling request from the terminal device, and obtain the identifierof the terminal device from the scheduling request.

Optionally, the identifier of the terminal device may include, forexample, at least one of the following identifiers: a cell radio networktemporary identifier (C-RNTI), a random access radio network temporaryidentifier (RA-RNTI), a temporary C-RNTI, and a transmit power controlradio network temporary identifier (TPC-RNTI), and this is not limitedin this embodiment of this application.

Optionally, the network device may obtain the first bandwidth in aplurality of manners, and this is not limited in this embodiment of thisapplication.

In an optional embodiment, the network device may configure the firstbandwidth for the terminal device.

Optionally, the network device may obtain the PTRS information of theterminal device in a plurality of manners, and this is not limited inthis embodiment of this application.

In an optional embodiment, the network device may configure the PTRSinformation for the terminal device.

In another optional embodiment, the network device may determine thePTRS information of the terminal device based on the first bandwidth anda first mapping relationship. The first mapping relationship is used toindicate a correspondence between the first bandwidth and the PTRSinformation.

Optionally, the network device and the terminal device may pre-agree onthe first mapping relationship, or the network device may configure thefirst mapping relationship for the terminal device by using higher layersignaling.

For example, the network device and the terminal device may pre-agreethat, the PTRS is not to be mapped when a value of the first bandwidthis less than a first preset value; the frequency domain density of thePTRS is 1 (the frequency domain interval is one RB) when the value ofthe first bandwidth is greater than or equal to the first preset valueand less than a second preset value; the frequency domain density of thePTRS is 2 when the value of the first bandwidth is greater than or equalto the second preset value and less than a third preset value; thefrequency domain density of the PTRS is 4 when the value of the firstbandwidth is greater than or equal to the third preset value and lessthan a fourth preset value; the frequency domain density of the PTRS is8 when the value of the first bandwidth is greater than or equal to thefourth preset value; and so on. The first preset value, the secondpreset value, the third preset value, and the fourth preset value are inascending order.

Optionally, in S310, the resource block offset of the frequency domainposition of the PTRS may mean that an offset of the frequency domainposition of the PTRS is measured in RBs, in other words, the offset ofthe frequency domain position of the PTRS is an RB-level offset.

It should be further understood that the resource block offset of thefrequency domain position of the PTRS may be understood as a resourceblock offset of a frequency domain position of the PTRS in a relativeRB.

It should be further understood that the frequency domain position ofthe PTRS may be understood as a frequency domain position to which aPTRS symbol in a sequence of the PTRS is mapped.

It should be further understood that when the network device allocates Kphysical resource blocks (PRB) to the terminal device, relative RBswhose sequence numbers (or numbers or indexes) are 0, 1, . . . , and K−1may be obtained in ascending order of sequence numbers of the K PRBs,where K is an integer greater than 0. For example, the network deviceallocates four PRBs whose sequence numbers are 0, 1, 6, and 7 to theterminal device, and four relative RBs whose sequence numbers are 0, 1,2, and 3 are obtained in ascending order of sequence numbers.

Optionally, the K physical resource blocks may be contiguous ornoncontiguous, and this is not limited in this embodiment of thisapplication.

It should be further understood that a frequency domain density N of aPTRS may mean that a frequency domain interval of the PTRS is N relativeRBs. In this case, a PTRS symbol 0 in a sequence of the PTRS correspondsto one of the relative RBs 0 to N−1, a PTRS symbol 1 corresponds to oneof the relative RBs N to 2*N−1, and so on, to obtain a relative RBcorresponding to each PTRS symbol in the sequence of the PTRS.

Specifically, a frequency domain position of a PTRS symbol M in thesequence of the PTRS in a relative RB may be a relative RB Δf+M*N, whereΔf indicates the resource block offset of the frequency domain position,N indicates the frequency domain density of the PTRS, and M is aninteger greater than or equal to 0.

Optionally, the network device may determine the resource block offsetof the frequency domain position of the PTRS based on at least one ofthe PTRS information, the identifier of the terminal device, and thefirst bandwidth, and this is not limited in this embodiment of thisapplication.

In an optional embodiment, the network device may determine the resourceblock offset of the frequency domain position of the PTRS based on thefrequency domain density of the PTRS and the identifier of the terminaldevice.

Optionally, when the frequency domain interval of the PTRS is FD_(step)and the identifier (ID) of the terminal device is ID_(UE), the networkdevice determines the resource block offset Δf in the following manners:

Manner 1: Δf=mod(ID_(UE), FD_(step)), where a value range of Δf is {0,1, . . . , FD_(step)−1} (For RB-level offset, the value can't exceed thefrequency interval between two adjacent PTRS, which is FD_(step) iffrequency density is every FD_(step)th RB, and modular operation can beintroduced to derive the RB-level offset from ID_(UE), illustrated as:Δf=mod(ID_(UE), FD_(step))).

Manner 2: Δf=ID_(UE){b₀, b₁, b₂, . . . b_(L-1)}, where a value range ofΔf is {0, 1, . . . , FD_(step)−1}, ID_(UE){b₀, b₁, b₂, . . . b_(L-1)}indicates that a bit b_(i) in ID_(UE) is used to determine the resourceblock offset, i={0, 1, 2, . . . , L−1}, in other words, there are atotal of L bits, L=ceil(log₂ ^(FD) ^(step) ), and the L bits are indescending order of bit significance from left to right.

Optionally, when 2^(L)>FD_(step), Δf=mod(ID_(UE){b₀, b₁, b₂, . . . ,b_(L-1)}, FD_(step)), where ceil(⋅) indicates rounding up.

However, in some special scenarios, some improper resource block offsetsmay be determined by the network device based on the PTRS informationand the identifier of the terminal device. Consequently, a relativelysmall quantity of PTRSs are mapped in the bandwidth scheduled by thenetwork device for the terminal device, and even a case in which no PTRSis mapped in the first bandwidth may occur, thereby affecting phasenoise estimation.

It should be understood that a quantity of PTRSs in this embodiment ofthis application may be understood as a quantity of PTRS symbols.

For example, assuming that the frequency domain interval of the PTRS is4, the resource block offset may be 0 RBs, one RB, two RBs, or threeRBs. When the first bandwidth is relatively small, the following problemmay exist:

When the first bandwidth is two RBs, if the resource block offset is 0RBs or one RB, a maximum quantity 1 of PTRSs are mapped in the firstbandwidth; or if the resource block offset is two RBs or three RBs, aminimum quantity 0 of PTRSs are mapped in the first bandwidth. In otherwords, if the first bandwidth is two RBs, no PTRS is mapped in the twoRBs when the resource block offset is relatively large.

When the first bandwidth is six RBs, if the resource block offset is 0RBs or one RB, a maximum quantity 2 of PTRSs are mapped in the firstbandwidth; or if the resource block offset is two RBs or three RBs, aminimum quantity 1 of PTRSs are mapped in the first bandwidth. In otherwords, if the first bandwidth is six RBs, a quantity of PTRSs is reducedby half when the resource block offset is relatively large.

In other words, under some conditions, for example, when the resourceblock offset is relatively small, a quantity of PTRSs mapped in thefirst bandwidth is relatively large; however, under some otherconditions, for example, when the resource block offset is relativelylarge, a quantity of PTRSs mapped in the first bandwidth may be lessthan a quantity of PTRSs mapped in the first bandwidth when the resourceblock offset is 0 RBs, and the quantity of PTRSs may be even 0.

In another optional embodiment, that the network device determines theresource block offset of the frequency domain position of the PTRS basedon the PTRS information and the identifier of the terminal device may bethat when a first condition is satisfied, the network device determinesthe resource block offset of the frequency domain position of the PTRSbased on the PTRS information and the identifier of the terminal device.

Optionally, the first condition may be at least one of the followingconditions:

(1) A ratio of the first bandwidth to the frequency domain density ofthe PTRS is greater than a first threshold.

(2) The ratio of the first bandwidth to the frequency domain density ofthe PTRS is an integer.

(3) A maximum quantity of PTRSs that can be mapped under the conditionsof the PTRS information and the first bandwidth is greater than a thirdthreshold.

(4) A minimum quantity of PTRSs that can be mapped under the conditionsof the PTRS information and the first bandwidth is greater than a fourththreshold.

(5) A ratio of the minimum quantity of PTRSs to the maximum quantity ofPTRSs is greater than a second threshold.

(6) The first bandwidth is greater than a fifth threshold.

When the first condition is not satisfied, a quantity of PTRSs mapped inthe first bandwidth may significantly decrease.

Optionally, in S310, that the network device determines the resourceblock offset based on the PTRS information, the identifier of theterminal device, and the first bandwidth may be that when a secondcondition is satisfied, the network device may determine the resourceblock offset based on the PTRS information, the identifier of theterminal device, and the first bandwidth.

Optionally, the second condition may be at least one of the followingconditions:

(1) A ratio of the first bandwidth to the frequency domain density ofthe PTRS is less than or equal to a first threshold.

(2) The ratio of the first bandwidth to the frequency domain density ofthe PTRS is a non-integer.

(3) A maximum quantity of PTRSs that can be mapped under the conditionsof the PTRS information and the first bandwidth is less than or equal toa third threshold.

(4) A minimum quantity of PTRSs that can be mapped under the conditionsof the PTRS information and the first bandwidth is less than or equal toa fourth threshold.

(5) A ratio of the minimum quantity of PTRSs to the maximum quantity ofPTRSs is less than or equal to a second threshold.

(6) The first bandwidth is less than or equal to a fifth threshold.

Optionally, one or more of the first threshold to the fifth thresholdmay be pre-agreed on by the network device and the terminal device, ormay be configured by the network device for the terminal device by usingfirst signaling, and this is not limited in this embodiment of thisapplication.

Optionally, the first signaling may be radio resource control (RRC)signaling, Media Access Control (MAC) control element (CE) signaling, ordownlink control information (DCI) signaling, and this is not limited inthis embodiment of this application.

In an optional embodiment, when the second condition is satisfied, thenetwork device may determine second bandwidth based on the PTRSinformation and the first bandwidth, and determine the resource blockoffset based on the second bandwidth and the identifier of the terminaldevice.

Optionally, when the frequency domain interval of the PTRS is FD_(step)and the first bandwidth is BW₁, the network device may determine thesecond bandwidth BW₂ in the following manners:

Manner 1: BW₂=mod(BW₁, FD_(step)), where mod(⋅) indicates a modulooperation.

Manner 2: BW₂=BW₁−(N_(max)−1)*FD_(step), where N_(max) is a maximumquantity of PTRSs that can be mapped in the first bandwidth, namely, aquantity of PTRSs that can be mapped when the offset is 0 RBs.

For example, when the first bandwidth is six RBs and the frequencydomain interval is four RBs, the second bandwidth is two RBs.

Optionally, when the second bandwidth is BW₂ and the identifier of theterminal device is ID_(UE), the network device may determine theresource block offset Δf in the following manners, where a value rangeof Δf is {0, 1, 2, . . . , BW₂−1}:

Manner 1: Δf=mod(ID_(UE), BW₂).

For example, when the first bandwidth is two RBs and the frequencydomain interval is four RBs, if the second bandwidth is two RBs, aresource block offset of a terminal device whose ID_(UE) equals to 0 is0 RBs, a resource block offset of a terminal device whose ID_(UE) equalsto 1 is one RB, a resource block offset of a terminal device whoseID_(UE) equals to 2 is 0 RBs, and a resource block offset of a terminaldevice whose ID_(UE) equals to 3 is one RB.

By considering the value of FD_(step) is limited to 2 or 4, integerpower of 2, L bits of ID_(UE) can be extracted to express the offset,where L equals to the log₂(FD_(step)).

According to the previous methods, for a same scheduled BW₁, the numberof PTRS for different UE may be different on some scenarios, e.g., iffrequency density is every 4th RB, and scheduled BW₁ is 6RB, then thenumber of PTRS can be 1 or 2, leading a large difference among users.Additional limitation on the offset can be introduces, such as replacethe “frequency density FD_(step)” in Equation 1 (Δf=mod(ID_(UE),FD_(step))) to modular BW₂, satisfy the equation BW₂=mod(BW₁,FD_(step)).

Manner 2: Δf=mod(mod(ID_(UE), FD_(step)), BW₂).

For example, when the first bandwidth is two RBs and the frequencydomain interval is four RBs, if the second bandwidth is two RBs, aresource block offset of a terminal device whose ID_(UE) equals to 0 is0 RBs, a resource block offset of a terminal device whose ID_(UE) equalsto 1 is one RB, a resource block offset of a terminal device whoseID_(UE) equals to 2 is 0 RBs, and a resource block offset of a terminaldevice whose ID_(UE) equals to 3 is one RB.

Manner 3: Δf=min(mod(ID_(UE), FD_(step)), BW₂−1), where min(⋅) indicatesobtaining a minimum value.

For example, when the first bandwidth is two RBs and the frequencydomain interval is four RBs, if the second bandwidth is two RBs, aresource block offset of a terminal device whose ID_(UE) equals to 0 is0 RBs, a resource block offset of a terminal device whose ID_(UE) equalsto 1 is one RB, a resource block offset of a terminal device whoseID_(UE) equals to 2 is one RB, and a resource block offset of a terminaldevice whose ID_(UE) equals to 3 is one RB.

Manner 4: Δf=ID_(UE){b₀, b₁, . . . , b_(L-1)}, where ID_(UE){b₀, b₁, . .. , b_(L-1)} indicates that a bit b_(i) in ID_(UE) is used to determinethe offset, i={0, 1, 2 . . . , L−1}, in other words, there are a totalof L bits, and the L bits are in descending order of bit significancefrom left to right.

Optionally, when 2^(L)>BW₂, Δf=mod(ID_(UE){b₀, b₁, . . . , b_(L-1)},BW₂), where ceil(⋅) indicates rounding up.

For example, when the first bandwidth is two RBs and the frequencydomain interval is four RBs, the second bandwidth is two RBs, and L=1,that is, ID_(UE){b₀}.

Optionally, when b₀=0, that is, a bit 0 (a least significant bit) inID_(UE) is used to determine the offset, a resource block offset of aterminal device whose ID_(UE) equals to 0 is 0 RBs, a resource blockoffset of a terminal device whose ID_(UE) equals to 1 is one RB, aresource block offset of a terminal device whose ID_(UE) equals to 2 is0 RBs, and a resource block offset of a terminal device whose ID_(UE)equals to 3 is one RB. Optionally, when b₀=1, that is, a bit 1 (a secondbit) in ID_(UE) is used to determine the offset, a resource block offsetof a terminal device whose ID_(UE) equals to 0 is 0 RBs, a resourceblock offset of a terminal device whose ID_(UE) equals to 1 is 0 RBs, aresource block offset of a terminal device whose ID_(UE) equals to 2 isone RB, and a resource block offset of a terminal device whose ID_(UE)equals to 3 is one RB.

However, if the network device determines the resource block offsetbased on only the frequency domain interval and the identifier of theterminal device when the second condition is satisfied, when thefrequency domain interval is four RBs, a resource block offset of aterminal device whose ID_(UE) equals to 0 is 0 RBs, a resource blockoffset of a terminal device whose ID_(UE) equals to 1 is one RB, aresource block offset of a terminal device whose ID_(UE) equals to 2 istwo RBs, and a resource block offset of a terminal device whose ID_(UE)equals to 3 is three RBs.

Because the first bandwidth is only two RBs, the network device cannotperform, in the first bandwidth, transmission of a PTRS with theterminal device whose ID_(UE) equals to 2 or the terminal device whoseID_(UE) equals to 3, and therefore the network device and the twoterminal devices cannot perform noise estimation based on receivedPTRSs.

According to the reference signal transmission method provided in thisembodiment of this application, when the second condition is satisfied,the network device determines the resource block offset based on thePTRS information, the first bandwidth, and the identifier of theterminal device, so that under the second condition, the network deviceand each terminal device can transmit PTRSs, and perform noiseestimation based on received PTRSs.

It should be understood that during the determining of the resourceblock offset of the PTRS of the terminal device based on the identifierof the terminal device, the identifier of the terminal device may bemapped to the resource block offset of the PTRS by using a modulomethod, and when a ratio of the bandwidth (the first bandwidth)scheduled by the network device for the terminal device to the frequencydomain density of the PTRS is relatively small, a bandwidth remainder(the second bandwidth) may replace the original frequency domain densityin a modulo formula for mapping the identifier of the terminal device tothe resource block offset of the PTRS. A modular operation is providedto map the UE-ID to the RB-level offset. If the ratio of the scheduledBW to the PTRS frequency density is small, the modular BW will replacethe frequency density in the modular to map the UE-ID to the RB-leveloffset.

Optionally, when the network device determines BW₂ in Manner 2, when thefirst condition is satisfied, the network device may determine theresource block offset of the frequency domain position of the PTRS basedon the second bandwidth and the identifier of the terminal device.

Optionally, the network device may determine, in a plurality of manners,a maximum quantity of PTRSs or a minimum quantity of PTRSs that can bemapped under the conditions of the PTRS information and the firstbandwidth, and this is not limited in this embodiment of thisapplication.

In an optional embodiment, the network device may determine the maximumquantity of PTRSs based on the first bandwidth, the frequency domaindensity (the frequency domain interval) of the PTRS, and a smallestresource block offset, where the smallest resource block offset is 0when the frequency domain interval of the PTRS is FD_(step).

In another optional embodiment, the network device may determine theminimum quantity of PTRSs based on the first bandwidth, the frequencydomain density (the frequency domain interval) of the PTRS, and alargest resource block offset, where the largest resource block offsetis FD_(step)−1 when the frequency domain interval of the PTRS isFD_(step).

For example, when the first bandwidth is eight RBs and the frequencydomain density of the PTRS is that a PTRS symbol is mapped to one inevery four RBs, a value range of the resource block offset is {0, 1, 2,3}. It can be determined, based on the smallest resource block offset 0RBs, that a maximum quantity of PTRSs that can be mapped in the eightRBs is 2 (in other words, PTRSs are mapped to a RB 0 and a RB 4), and itcan be determined, based on the largest resource block offset three RBs,that a minimum quantity of PTRSs that can be mapped in the eight RBs is2 (in other words, PTRSs are mapped to a RB 3 and a RB 7).

For another example, when the first bandwidth is six RBs and thefrequency domain density of the PTRS is that a PTRS symbol is mapped toone in every four RBs, a value range of the resource block offset is {0,1, 2, 3}. It can be determined, based on the smallest resource blockoffset 0 RBs, that a maximum quantity of PTRSs that can be mapped in thesix RBs is 2 (in other words, PTRSs are mapped to RBs 0 and 4), and itcan be determined, based on the largest resource block offset three RBs,that a minimum quantity of PTRSs that can be mapped in the six RBs is 1(in other words, a PTRS is mapped to the RB 3).

S320. During S320, the terminal device determines the resource blockoffset of the frequency domain position of the PTRS based on the PTRSinformation, the identifier of the terminal device, and the firstbandwidth.

It should be understood that there is no order for performing S310 andS320.

Optionally, before S320, the terminal device may obtain the PTRSinformation, the identifier of the terminal device, and the firstbandwidth.

Optionally, the identifier of the terminal device may include, forexample, at least one of the following identifiers: a cell radio networktemporary identifier (C-RNTI), a random access radio network temporaryidentifier (RA-RNTI), a temporary C-RNTI, and a transmit power controlradio network temporary identifier (TPC-RNTI), and this is not limitedin this embodiment of this application.

Optionally, the terminal device may generate the identifier.

Optionally, the terminal device may obtain the first bandwidth in aplurality of manners, and this is not limited in this embodiment of thisapplication.

In an optional embodiment, the terminal device may receive firstconfiguration information sent by the network device, and obtain thefirst bandwidth from the first configuration information.

Optionally, the terminal device may obtain the PTRS information of theterminal device in a plurality of manners, and this is not limited inthis embodiment of this application.

In an optional embodiment, the terminal device may receive secondconfiguration information sent by the network device, and obtain thePTRS information from the second configuration information.

In another optional embodiment, the terminal device may receive firstconfiguration information sent by the network device, obtain the firstbandwidth from the first configuration information, and determine thePTRS information of the terminal device based on the first bandwidth anda first mapping relationship. The first mapping relationship is used toindicate a correspondence between the first bandwidth and the PTRSinformation.

Optionally, the network device and the terminal device may pre-agree onthe first mapping relationship, or the network device may configure thefirst mapping relationship for the terminal device by using higher layersignaling.

For example, the network device and the terminal device may pre-agreethat, the PTRS is not to be mapped when a value of the first bandwidthis less than a first preset value; the frequency domain density of thePTRS is 1 (the frequency domain interval is one RB) when the value ofthe first bandwidth is greater than or equal to the first preset valueand less than a second preset value; the frequency domain density of thePTRS is 2 when the value of the first bandwidth is greater than or equalto the second preset value and less than a third preset value; thefrequency domain density of the PTRS is 4 when the value of the firstbandwidth is greater than or equal to the third preset value and lessthan a fourth preset value; the frequency domain density of the PTRS is8 when the value of the first bandwidth is greater than or equal to thefourth preset value; and so on. The first preset value, the secondpreset value, the third preset value, and the fourth preset value are inascending order.

S330. During S330, the network device performs transmission of the PTRSwith the terminal device based on the resource block offset of thefrequency domain position of the PTRS, and correspondingly, the terminaldevice performs transmission of the PTRS with the network device basedon the resource block offset of the frequency domain position of thePTRS.

Optionally, S330 may be that the network device determines, based on theresource block offset of the frequency domain position of the PTRS, afrequency domain position of a relative RB to which the PTRS is to bemapped, determines, based on the frequency domain position of therelative RB to which the PTRS is to be mapped, a frequency domainposition of a PRB to which the PTRS is to be mapped, and performstransmission of the PTRS with the terminal device on the frequencydomain position of the PRB to which the PTRS is to be mapped.

Correspondingly, the terminal device determines, based on the resourceblock offset of the frequency domain position of the PTRS, the frequencydomain position of the relative RB to which the PTRS is to be mapped,determines, based on the frequency domain position of the relative RB towhich the PTRS is to be mapped, the frequency domain position of the PRBto which the PTRS is to be mapped, and performs transmission of the PTRSwith the network device on the frequency domain position of the PRB towhich the PTRS is to be mapped.

The following uses the network device as an example to describe how thenetwork device determines, based on the resource block offset of thefrequency domain position of the PTRS, the frequency domain position ofthe PRB to which the PTRS is to be mapped.

FIG. 4 is a schematic diagram of a relationship between a frequencydomain position of a relative RB to which a PTRS is to be mapped and afrequency domain position of a PRB to which the PTRS is to be mappedaccording to an embodiment of this application. As shown in FIG. 4, itis assumed that the network device schedules, for the terminal device, atotal of 12 noncontiguous PRBs whose sequence numbers are 0, 1, 6, 7, 8,9, 10, 11, 18, 19, 22, and 23, and a frequency domain density of a PTRSis 4.

Because the 12 PRBs scheduled by the network device are noncontiguous,and the frequency domain density of the PTRS is 4, in other words, asymbol is mapped to one in every four RBs, the network device needs todetermine a specific PRB to which the PTRS is to be mapped.

Optionally, it is assumed that there are a total of 12 contiguousrelative RBs whose sequence numbers are 0, 1, 2, . . . , and 11, and the12 noncontiguous PRBs successively correspond to the 12 relative RBs inascending order of sequence numbers of the PRBs. For example, a PRBwhose sequence number is 0 corresponds to a relative RB whose sequencenumber is 0, a PRB whose sequence number is 1 corresponds to a relativeRB whose sequence number is 1, a PRB whose sequence number is 6corresponds to a relative RB whose sequence number is 2, a PRB whosesequence number is 7 corresponds to a relative RB whose sequence numberis 3, . . . , and a PRB whose sequence number is 23 corresponds to arelative RB whose sequence number is 11.

When the frequency domain density that is of the PTRS and that isconfigured by the network device for the terminal device is 4 (in otherwords, a PTRS is mapped to one in every four RBs) and a resource blockoffset of a frequency domain position of the PTRS is one RB, a frequencydomain position of a relative RB to which the PTRS is to be mappedincludes the relative RB whose sequence number is 1, a relative RB whosesequence number is 5, and a relative RB whose sequence number is 9.

The network device may determine, based on the correspondence between arelative RB and a PRB, that a frequency domain position of a PRB towhich the PTRS is to be mapped includes the PRB whose sequence number is1, a PRB whose sequence number is 9, and a PRB whose sequence number is19.

Therefore, the network device may perform transmission of the PTRS withthe terminal device on the PRB whose sequence number is 1, the PRB whosesequence number is 9, and the PRB whose sequence number is 19.

It should be understood that the terminal device determines, in asimilar manner to the network device, the resource position of the PRBto which the PTRS is to be mapped. To avoid repetition, details are notdescribed herein again.

It should be further understood that the foregoing method fordetermining a relationship between a frequency domain position of arelative RB to which a PTRS is to be mapped and a frequency domainposition of a PRB to which the PTRS is to be mapped is also applicableto a scenario in which PRBs are contiguous, and this is not limited inthis embodiment of this application.

Optionally, in this embodiment of this application, at least onerelative RB in ascending order of numbers (or sequence numbers orindexes) may be obtained in ascending order of sequence numbers of atleast one VRB (virtual resource block) scheduled by the network device,and this is not limited in this embodiment of this application. Thenetwork device or the terminal device may determine, based on afrequency domain position of a relative RB to which the PTRS is to bemapped, a frequency domain position of a VRB to which the PTRS is to bemapped.

Optionally, the reference signal transmission method provided in thisembodiment of this application may be applied to an uplink transmissionscenario of a reference signal, or may be applied to a downlinktransmission scenario of a reference signal, and this is not limited inthis embodiment of this application.

In the downlink transmission scenario, S330 may be that the networkdevice sends the PTRS to the terminal device based on the resource blockoffset of the frequency domain position of the PTRS, andcorrespondingly, the terminal device receives, based on the resourceblock offset of the frequency domain position of the PTRS, the PTRS sentby the network device.

In the uplink transmission scenario, S330 may be that the terminaldevice sends the PTRS to the network device based on the resource blockoffset of the frequency domain position of the PTRS, andcorrespondingly, the network device receives, based on the resourceblock offset of the frequency domain position of the PTRS, the PTRS sentby the terminal device.

Optionally, after S330, the network device may perform phase noiseestimation based on the PTRS, and correspondingly, the terminal devicemay also perform phase noise estimation based on the PTRS.

According to the reference signal transmission method provided in thisembodiment of this application, because a multi-user multiple-inputmultiple-output (MU-MIMO) technology supports non-orthogonalmultiplexing between PTRS ports and between a PTRS port and data, afrequency domain position of at least one resource block to which a PTRSof the terminal device is to be mapped is determined based on at leastone of the identifier of the terminal device, the PTRS information, andthe first bandwidth, so that paired PTRSs of the terminal device can bemapped to different frequency domain positions by using a resource blockoffset. In other words, the PTRS of the terminal device is interfered bydata of another terminal device, and PTRS interference of the terminaldevice is more random by randomizing the data of the another terminaldevice, to help randomize the PTRS interference of the terminal device,thereby stabilizing performance of PTRS-based noise estimation.

It should be understood that according to the method 300, the networkdevice or the terminal device can determine a frequency domain positionof a resource block (PRB) to which a PTRS is to be mapped. The followingdescribes in detail how the network device or the terminal devicedetermines a frequency domain position of a resource element to whichthe PTRS is to be mapped in the resource block.

FIG. 5 shows a reference signal transmission method 500 according to anembodiment of this application. The transmission method 500 may beapplied to the communications system 100 shown in FIG. 1.

S510. During S510, a network device determines a second frequency domainoffset based on a first frequency domain offset and at least onesubcarrier to which a DMRS of a terminal device is to be mapped in afirst resource block, where the first resource block is a resource blockto which a first PTRS of the terminal device is to be mapped, the firstfrequency domain offset is used to determine, from the first resourceblock, a frequency domain position of a resource element to which thefirst PTRS is to be mapped, and the second frequency domain offset isused to determine, from the at least one subcarrier, a frequency domainposition to which the first PTRS is to be mapped.

Optionally, the first resource block is a resource block to which thefirst PTRS of the terminal device is to be mapped, and the firstresource block may be determined according to the foregoing method 300,or may be determined in another manner. This is not limited in thisembodiment of this application.

Optionally, the network device may obtain, in a plurality of manners,the at least one subcarrier to which the DMRS of the terminal device isto be mapped in the first resource block, and this is not limited inthis embodiment of this application.

In an optional embodiment, the network device may configure, for theterminal device, the at least one subcarrier to which the DMRS is to bemapped.

It should be understood that because a resource element/a subcarrier towhich the PTRS is to be mapped needs to be in a subcarrier set occupiedby a DMRS port associated with the first PTRS, the network device maydetermine, based on scheduling information of the DMRS, at least onesubcarrier occupied by the DMRS port, associated with the PTRS, in onesymbol in the first resource block. The at least one subcarrier isdenoted as a subcarrier set S1={RE₁, RE₂, . . . , RE_(P)}, RE_(i)indicates a number/an index of a subcarrier to which the DMRS port is tobe mapped in the first resource block, a value range of i is {1, . . . ,P}, P is a total quantity of subcarriers occupied by the DMRS port inone symbol in the first resource block, and RE₁<RE₂<RE₃, . . . ,<RE_(P).

Optionally, FIG. 6 is a schematic diagram of a frequency domain positionof a subcarrier to which a DMRS port Q₀/Q₁ is to be mapped in a firstresource block. As shown in FIG. 6, a frequency domain offset 0 to afrequency domain offset 11 respectively correspond to subcarrier 0 tosubcarrier 11 in one symbol in the first resource block. When a DMRSconfiguration is type 1, a subcarrier set occupied by one DMRS port inone RB is S1={0, 2, 4, 6, 8, 10} respectively corresponding to RE₁ toRE₆, and in this case, P=6. When a to-be-mapped DMRS is of a type 2, asubcarrier set occupied by one DMRS port in one RB is S1={0, 1, 6, 7}respectively corresponding to RE₁ to RE₄, and in this case, P=4.

It should be understood that Q₀/Q₁ of a DMRS port in this embodiment ofthis application indicates a number/an identifier of the DMRS port.

Optionally, when a subcarrier occupied by the DMRS port associated withthe PTRS includes a direct current (DC) subcarrier, to avoid a conflictbetween the PTRS and the DC subcarrier, a subcarrier number/index of thedirect current subcarrier needs to be removed from the subcarrier set,to obtain a new subcarrier set S2=S1−{RE_(DC)}, where RE_(DC) is thenumber/index of the DC subcarrier to which the PTRS is to be mapped inthe first resource block.

For example, as shown in FIG. 6, when a port Q₀/Q₁ of the type 1 isconfigured for the DMRS, S1={0, 2, 4, 6, 8, 10}; if the DC subcarrier(subcarrier 6) coincides with a fourth subcarrier to which the DMRS portis to be mapped in the first resource block, that is, RE₄ in S1, RE₄ inthe set S1 is removed to obtain a new subcarrier set S2={0, 2, 4, 8, 10}respectively corresponding to RE₁ to RE₅.

For another example, as shown in FIG. 6, when a port Q₀/Q₁ of the type 2is configured for the DMRS, S1={0, 1, 6, 7}, if no DC subcarrier existsin the first resource block for the DMRS port, S1 does not need to beprocessed, and S2=S1={0, 1, 6, 7}.

Because the DC subcarrier is removed from the subcarrier set occupied bythe DMRS port associated with the first PTRS, the following problem canbe avoided: the first PTRS is mapped to a frequency domain position onwhich the DC subcarrier is located, which causes a conflict between thePTRS and the DC subcarrier.

It should be understood that the first frequency domain offset indicatesa resource element offset of the frequency domain position to which thefirst PTRS is to be mapped in the first resource block.

Optionally, the network device may obtain the first frequency domainoffset in an explicit indication manner or an implicit indicationmanner, and this is not limited in this embodiment of this application.

In the explicit indication manner, the first frequency domain offset maybe configured by the network device for the terminal device by usingsecond signaling.

Optionally, the second signaling may be RRC signaling, MAC CE signaling,or DCI signaling, and this is not limited in this embodiment of thisapplication.

In the implicit indication manner, the network device may determine thefirst frequency domain offset based on reference information of theterminal device, where the reference information includes at least oneof an identifier of the terminal device and scheduling information ofthe terminal device.

Optionally, the scheduling information of the terminal device mayinclude, for example, at least one of the following information:scheduling information of the demodulation reference signal (DMRS),scheduling information of the PTRS, scheduling information of areference signal (RS) such as scheduling information of a soundingreference signal (SRS), and scheduling information of a codeword. Thisis not limited in this embodiment of this application.

Optionally, the scheduling information of the DMRS may include at leastone of a port number, a port quantity, a port pattern, a resourceelement mapping (resource element mapping), a sequence scramblingindex/number, and a subcarrier sequence number/resource element of theDMRS. The scheduling information of the first PTRS may include at leastone of a port number, a port quantity, a frequency domain density, aresource element mapping, and a sequence scrambling index/number of thefirst PTRS. The scheduling information of the SRS may include at leastone of a port number, a port quantity, a port pattern, a resourceelement mapping, a sequence scrambling index/number, and a subcarriersequence number/resource element of the SRS. The scheduling informationof the codeword may include a codeword number and/or a codeword quantityof the codeword.

Optionally, the network device may determine the first frequency domainoffset k_(offset) in the following manners:

Manner 1: k_(offset)=P_(DMRS), or k_(offset)=P_(PTRS), ork_(offset)=ID_(UE), or k_(offset)=ID_(SC), or k_(offset)=ID_(Cell).

Where: P_(DMRS) indicates a DMRS port number of the terminal device,P_(PTRS) indicates a PTRS port number of the terminal device, ID_(UE)indicates the identifier of the terminal device, ID_(SC) indicates asequence scrambling ID of the first PTRS or a sequence scrambling ID ofthe DMRS port associated with the PTRS, and ID_(Cell) indicates a cellidentifier.

Manner 2: k_(offset)=mod(P_(DMRS), 12), or k_(offset)=mod(P_(PTRS), 12),or k_(offset)=mod(ID_(UE), 12), or k_(offset)=mod(ID_(SC), 12), ork_(offset)=mod(ID_(Cell), 12).

Manner 3: k_(offset)=P_(DMRS)−P_(DMRS_min), ork_(offset)=P_(PTRS)−P_(PTRS_min).

Where: P_(DMRS_min) indicates a smallest DMRS port number, andP_(PTRS_min) indicates a smallest PTRS port number.

It should be understood that because the frequency domain position thatis of the resource element to which the first PTRS is to be mapped andthat is determined by the network device based on the first frequencydomain offset possibly cannot exactly correspond to a subcarrier towhich the DMRS is to be mapped, a mapping relationship is required tomap the first frequency domain offset to a subcarrier set of the DMRS,in other words, the second frequency domain offset for mapping the firstPTRS to the subcarrier set needs to be determined.

For RE-level offset, the PTRS should be mapped on the subcarrier whichcarried the associated DMRS also. To realize the characteristics, a setwhich only including the subcarriers of the associated DMRS port andpreclude the DC tone is defined, and the RE-level offset k implicitly orexplicitly indicated is mapped to the relative offset k′ in the set, andthe k'th+1 subcarrier is chosen for PTRS mapping within a given RB, andthe mapping rule between k and k′ can be denoted as with k′=mod(k, S),where S is the size of the set.

For example, as shown in FIG. 6, when the first frequency domain offsetis 11 and a DMRS port of the type 1 is configured, it may be determined,based on the first offset, that the first PTRS is to be mapped tosubcarrier 11, and because the subcarrier set S2={0, 2, 4, 8, 10} (theDC subcarrier has been removed from S1), it can be learned thatsubcarrier 11 does not belong to S2.

Optionally, when the first frequency domain offset is k_(offset) and thesubcarrier set S2 includes P subcarriers, the network device maydetermine the second frequency domain offset in the following manners:

Manner 1: k′_(offset)=mod(k_(offset), P).

P indicates a quantity of subcarriers in the set S2.

Manner 2: k′_(offset)=Int(k_(offset)*P/12).

For example, as shown in FIG. 6, when the first frequency domain offsetis 11, the subcarrier set S2={0, 2, 4, 8, 10}, namely, P=5, it may bedetermined, in Manner 1, that the second frequency domain offset is 1,in other words, the first PTRS is to be mapped to RE₂ in the subcarrierset S1, that is, subcarrier 2.

S520. During S520, the network device determines, based on a frequencydomain position of the at least one subcarrier and the second frequencydomain offset, the frequency domain position to which the first PTRS isto be mapped.

Optionally, the network device determines, based on the second frequencydomain offset and a position of each subcarrier in the subcarrier set,the frequency domain position to which the first PTRS is to be mapped.

For example, when the subcarrier set is S2={0, 2, 4, 8, 10} and thesecond frequency domain offset of the first PTRS is 3, the frequencydomain position to which the first PTRS is to be mapped is RE₄, in otherwords, the first PTRS is mapped to the fourth subcarrier (subcarrier 8)in S2.

S530. During S530, the terminal device determines the second frequencydomain offset based on the first frequency domain offset and the atleast one subcarrier to which the DMRS of the terminal device is to bemapped in the first resource block.

S540. During S540, the terminal device determines, based on thefrequency domain position of the at least one subcarrier and the secondfrequency domain offset, the frequency domain position to which thefirst PTRS is to be mapped.

It should be understood that S530 is similar to S510 and S540 is similarto S520. To avoid repetition, details are not described herein againwith respect to S.

It should be further understood that there is no order for performingS510 and S530.

S550. During S550, the network device performs transmission of the firstPTRS with the terminal device based on the frequency domain position towhich the first PTRS is to be mapped, and correspondingly, the terminaldevice performs transmission of the first PTRS with the network devicebased on the frequency domain position to which the first PTRS is to bemapped.

Optionally, when positions to which two different PTRS ports are to bemapped in the first resource block are the same, for example, as shownin FIG. 6, when a DMRS of a type 1 is configured, assuming that secondfrequency domain offsets determined for a first PTRS and a second PTRSare both 1 (in other words, both the PTRS 1 and the PTRS 2 are to bemapped to subcarrier 4 in the subcarrier set occupied by the DMRS port),the first PTRS and the second PTRS interfere with each other. Therefore,it may be ensured, in the following manners, that frequency domainpositions to which the two different PTRSs are to be mapped aredifferent.

Optionally, the first PTRS and the second PTRS may correspond todifferent PTRS ports of a same terminal device, or may correspond todifferent terminal devices. This is not limited in this embodiment ofthis application.

Manner 1: k′_(offset1)=k′_(offset2)+1, or k′_(offset1)=k′_(offset2)−1.

Where: k′_(offset1) indicates a second frequency domain offset of thefirst PTRS, and k′_(offset2) indicates a second frequency domain offsetof the second PTRS.

Assuming that the subcarrier set is S2={RE₁, RE₂, . . . RE_(P)}, whenthe second frequency domain offset of the first PTRS is the same as thefrequency domain offset of the second PTRS, the network device maydetermine RE_(j−1) or RE_(j+1) adjacent to RE_(j) in the subcarrier setas a frequency domain position of a resource element to which the firstPTRS is to be mapped, and perform transmission of the first PTRS withthe terminal device on RE_(j−1) or RE_(j+1), where RE_(j) indicates thefrequency domain position of the resource element corresponding to thesecond frequency domain offset of the first PTRS, and a value range of jis {1, 2, . . . , P}.

Optionally, when an adjacent subcarrier falls beyond a range, a valuemay be cyclically used based on a quantity of elements in the set.

For example, when j−1=0, j−1 may be set to P, in other words, when thevalue is less than a smallest number, a cyclic process is performed tothe end of the set to obtain a largest value.

For example, when j+1=P+1, j−1 may be set to 1, in other words, when thevalue is greater than a largest number, a cyclic process is performed tothe start of the set to obtain a smallest value.

Correspondingly, the network device performs transmission of the secondPTRS with the terminal device on RE_(j).

Manner 2: k′_(offset2)=k′_(offset1)+1, or k′_(offset2)=k′_(offset1)−1.

Assuming that the subcarrier set is S2={RE₁, RE₂, . . . , RE_(P)}, whenthe second frequency domain offset of the first PTRS is the same as thefrequency domain offset of the second PTRS, the network device maydetermine RE_(j−1) or RE_(j+1) adjacent to RE_(j) in the subcarrier setas a frequency domain position of a resource element to which the secondPTRS is to be mapped, and perform transmission of the second PTRS withthe terminal device on RE_(j−1) or RE_(j+1), where RE_(j) indicates thefrequency domain position of the resource element corresponding to thesecond frequency domain offset of the second PTRS, and a value range ofj is {1, 2, . . . , P}.

Optionally, when an adjacent subcarrier falls beyond a range, a valuemay be cyclically used based on a quantity of elements in the set.

For example, when j−1=0, j−1 may be set to P, in other words, when thevalue is less than a smallest number, a cyclic process is performed tothe end of the set to obtain a largest value.

For example, when j+1=P+1, j−1 may be set to 1, in other words, when thevalue is greater than a largest number, a cyclic process is performed tothe start of the set to obtain a smallest value.

Correspondingly, the network device performs transmission of the firstPTRS with the terminal device on RE_(j).

For example, it is assumed that the subcarrier set is S2={0, 2, 4, 8,10}, and both the second frequency domain offset of the first PTRS andthe second frequency domain offset of the second PTRS are 2, in otherwords, both the first PTRS and the second PTRS are to be mapped to thethird subcarrier (subcarrier 4).

Optionally, the network device may perform transmission of the firstPTRS with the terminal device on the third subcarrier (subcarrier 4),and perform transmission of the second PTRS with the terminal device onthe second subcarrier (subcarrier 2)/the fourth subcarrier (subcarrier8).

Optionally, the network device may perform transmission of the secondPTRS with the terminal device on the third subcarrier (subcarrier 4),and perform transmission of the first PTRS with the terminal device onthe second subcarrier (subcarrier 2)/the fourth subcarrier (subcarrier8).

It should be understood that a relative offset (the second frequencydomain offset) in a subcarrier set may be defined, and is used toindicate a subcarrier to which a PTRS is to be mapped in a givenresource block. The subcarrier set includes a subcarrier occupied by aDMRS port associated with the PTRS, and includes no direct currentsubcarrier. A relative offset among the subcarrier set only includes thesubcarrier occupied by the associated DMRS port, and does not includethe DC tone.

According to the reference signal transmission method provided in thisembodiment of this application, when the frequency domain position ofthe resource element to which the first PTRS is to be mapped is the sameas the frequency domain position of the resource element to which thesecond PTRS is to be mapped, the frequency domain position of theresource element to which the first PTRS is to be mapped or thefrequency domain position of the resource element to which the secondPTRS is to be mapped may be adjusted, so that the first PTRS and thesecond PTRS are mapped to two different subcarriers in the subcarrierset occupied by the DMRS port, and the two subcarriers have adjacentnumbers or indexes in the subcarrier set, thereby avoiding mutualinterference between the first PTRS and the second PTRS.

With reference to FIG. 1 to FIG. 6, the foregoing describes in detailthe reference signal transmission method provided in the embodiments ofthis application. With reference to FIG. 7 to FIG. 14, the followingdescribes a reference signal transmission apparatus provided in theembodiments of this application.

FIG. 7 shows a reference signal transmission apparatus 700 according toan embodiment of this application. The transmission apparatus 700includes: a processing unit 710, configured to determine a resourceblock offset of a frequency domain position of a phase trackingreference signal (PTRS) of a terminal device based on PTRS informationof the terminal device, an identifier of the terminal device, and firstbandwidth, where the PTRS information includes a frequency domaindensity or a frequency domain interval of the PTRS, and the firstbandwidth is bandwidth scheduled for the terminal device; and atransceiver unit 720, configured to perform transmission of the PTRSwith the terminal device based on the resource block offset that is ofthe frequency domain position of the PTRS and that is determined by theprocessing unit 710.

Optionally, the processing unit is specifically configured to: beforedetermining the resource block offset of the frequency domain positionof the PTRS of the terminal device based on the PTRS information of theterminal device, the identifier of the terminal device, and the firstbandwidth, determine a maximum quantity of PTRSs and a minimum quantityof PTRSs that can be mapped under the conditions of the PTRS informationand the first bandwidth; and when a ratio of the minimum quantity ofPTRSs to the maximum quantity of PTRSs is less than or equal to a firstpreset value, determine the resource block offset of the frequencydomain position of the PTRS based on the PTRS information of theterminal device, the identifier of the terminal device, and the firstbandwidth.

Optionally, the processing unit is specifically configured to: performmodulo processing on the first bandwidth based on the PTRS information,to obtain second bandwidth; and determine the resource block offset ofthe frequency domain position of the PTRS based on the second bandwidthand the identifier of the terminal device.

Optionally, the processing unit is specifically configured to: when theratio of the minimum quantity of PTRSs to the maximum quantity of PTRSsis greater than the first preset value, determine the resource blockoffset of the frequency domain position of the PTRS based on the PTRSinformation and the identifier of the terminal device.

It should be understood that the transmission apparatus 700 herein isembodied in the form of functional units. The term “unit” herein may bean application-specific integrated circuit (ASIC), an electroniccircuit, a processor (for example, a shared processor, a dedicatedprocessor, or a group processor) for executing one or more software orfirmware programs, a memory, a combinational logic circuit, and/oranother appropriate component supporting the described functions. In anoptional example, a person skilled in the art may understand that thetransmission apparatus 700 may be specifically the network device in theembodiment of the transmission method 300, and the transmissionapparatus 700 may be configured to perform procedures and/or steps thatare corresponding to the network device in the embodiment of the method300. To avoid repetition, details are not described herein again.

FIG. 8 shows a reference signal transmission apparatus 800 according toan embodiment of this application. The transmission apparatus 800includes: a processing unit 810, configured to determine a resourceblock offset of a frequency domain position of a phase trackingreference signal (PTRS) based on PTRS information, an identifier of thetransmission apparatus, and first bandwidth, where the PTRS informationincludes a frequency domain density or a frequency domain interval ofthe PTRS, and the first bandwidth is bandwidth scheduled by a networkdevice for the transmission apparatus; and a transceiver unit 820,configured to perform transmission of the PTRS with the network devicebased on the resource block offset that is of the frequency domainposition of the PTRS and that is determined by the processing unit 810.

Optionally, the processing unit is specifically configured to: beforedetermining the resource block offset of the frequency domain positionof the PTRS based on the PTRS information, the identifier of thetransmission apparatus, and the first bandwidth, determine a maximumquantity of PTRSs and a minimum quantity of PTRSs that can be mappedunder the conditions of the PTRS information and the first bandwidth;and when a ratio of the minimum quantity of PTRSs to the maximumquantity of PTRSs is less than or equal to a first preset value,determine the resource block offset of the frequency domain position ofthe PTRS based on the PTRS information, the identifier of thetransmission apparatus, and the first bandwidth.

Optionally, the processing unit is specifically configured to: performmodulo processing on the first bandwidth based on the PTRS information,to obtain second bandwidth; and determine the resource block offset ofthe frequency domain position of the PTRS based on the second bandwidthand the identifier of the transmission apparatus.

Optionally, the processing unit is specifically configured to: when theratio of the minimum quantity of PTRSs to the maximum quantity of PTRSsis greater than the first preset value, determine the resource blockoffset of the frequency domain position of the PTRS based on the PTRSinformation and the identifier of the transmission apparatus.

It should be understood that the transmission apparatus 800 herein isembodied in the form of functional units. The term “unit” herein may bean ASIC, an electronic circuit, a processor (for example, a sharedprocessor, a dedicated processor, or a group processor) for executingone or more software or firmware programs, a memory, a combinationallogic circuit, and/or another appropriate component supporting thedescribed functions. In an optional example, a person skilled in the artmay understand that the transmission apparatus 800 may be specificallythe terminal device in the embodiment of the transmission method 300,and the transmission apparatus 800 may be configured to performprocedures and/or steps that are corresponding to the terminal device inthe embodiment of the transmission method 300. To avoid repetition,details are not described herein again.

FIG. 9 shows a reference signal transmission apparatus 900 according toan embodiment of this application. The transmission apparatus 900includes: a processing unit 910, configured to: determine a secondfrequency domain offset based on a first frequency domain offset and atleast one subcarrier to which a demodulation reference signal (DMRS) ofa terminal device is to be mapped in a first resource block, where thefirst resource block is a resource block to which a first phase trackingreference signal (PTRS) of the terminal device is to be mapped, thefirst frequency domain offset is used to determine, from the firstresource block, a frequency domain position of a resource element towhich the first PTRS is to be mapped, and the second frequency domainoffset is used to determine, from the at least one subcarrier, afrequency domain position to which the first PTRS is to be mapped; anddetermine, based on a frequency domain position of the at least onesubcarrier and the second frequency domain offset, the frequency domainposition to which the first PTRS is to be mapped; and a transceiver unit920, configured to perform transmission of the first PTRS with theterminal device based on the frequency domain position to which thefirst PTRS is to be mapped and that is determined by the processing unit910.

In a possible implementation, the at least one subcarrier includes nodirect current subcarrier.

In a possible implementation, when both the frequency domain position towhich the first PTRS is to be mapped and a frequency domain position towhich a second PTRS of the terminal device is to be mapped are a firstsubcarrier in the at least one subcarrier, the transceiver unit isspecifically configured to: determine a second subcarrier based on thefirst subcarrier, where the second subcarrier is a subcarrier spacedfrom the first subcarrier by a minimum quantity of subcarriers in the atleast one subcarrier; and perform transmission of the first PTRS withthe terminal device on the second subcarrier.

In a possible implementation, the transmission apparatus furtherincludes an obtaining unit. The obtaining unit is configured to: beforethe second frequency domain offset is determined based on the firstfrequency domain offset and the at least one subcarrier to which theDMRS of the terminal device is to be mapped in the first resource block,obtain reference information of the terminal device, where the referenceinformation includes at least one of an identifier of the terminaldevice and scheduling information of the terminal device; and determinethe first frequency domain offset based on the reference information ofthe terminal device.

In a possible implementation, the scheduling information of the terminaldevice includes at least one of the following information: schedulinginformation of the DMRS, scheduling information of the first PTRS,scheduling information of a sounding reference signal (SRS), andscheduling information of a codeword.

It should be understood that the transmission apparatus 900 herein isembodied in the form of functional units. The term “unit” herein may bean ASIC, an electronic circuit, a processor (for example, a sharedprocessor, a dedicated processor, or a group processor) for executingone or more software or firmware programs, a memory, a combinationallogic circuit, and/or another appropriate component supporting thedescribed functions. In an optional example, a person skilled in the artmay understand that the transmission apparatus 900 may be specificallythe network device in the embodiment of the transmission method 500, andthe transmission apparatus 900 may be configured to perform proceduresand/or steps that are corresponding to the network device in theembodiment of the transmission method 500. To avoid repetition, detailsare not described herein again.

FIG. 10 shows a reference signal transmission apparatus 1000 accordingto an embodiment of this application. The transmission apparatus 1000includes a processing unit 1010, configured to: determine a secondfrequency domain offset based on a first frequency domain offset and atleast one subcarrier to which a demodulation reference signal (DMRS) ofthe transmission apparatus is to be mapped in a first resource block,where the first resource block is a resource block to which a firstphase tracking reference signal (PTRS) is to be mapped, the firstfrequency domain offset is used to determine, from the first resourceblock, a frequency domain position of a resource element to which thefirst PTRS is to be mapped, and the second frequency domain offset isused to determine, from the at least one subcarrier, a frequency domainposition to which the first PTRS is to be mapped; and determine, basedon a frequency domain position of the at least one subcarrier and thesecond frequency domain offset, the frequency domain position to whichthe first PTRS is to be mapped; and a transceiver unit 1020, configuredto perform transmission of the first PTRS with the network device basedon the frequency domain position to which the first PTRS is to be mappedand that is determined by the processing unit 1010.

In a possible implementation, the at least one subcarrier includes nodirect current subcarrier.

In a possible implementation, when both the frequency domain position towhich the first PTRS is to be mapped and a frequency domain position towhich a second PTRS of the transmission apparatus is to be mapped are afirst subcarrier in the at least one subcarrier, the transceiver unit isspecifically configured to: determine a second subcarrier based on thefirst subcarrier, where the second subcarrier is a subcarrier spacedfrom the first subcarrier by a minimum quantity of subcarriers in the atleast one subcarrier; and perform transmission of the first PTRS withthe network device on the second subcarrier.

In a possible implementation, the transmission apparatus furtherincludes an obtaining unit. The obtaining unit is configured to: beforethe second frequency domain offset is determined based on the firstfrequency domain offset and the at least one subcarrier to which theDMRS of the transmission apparatus is to be mapped in the first resourceblock, obtain reference information of the transmission apparatus, wherethe reference information includes at least one of an identifier of thetransmission apparatus and scheduling information of the transmissionapparatus; and determine the first frequency domain offset based on thereference information of the transmission apparatus.

In a possible implementation, the scheduling information of thetransmission apparatus includes at least one of the followinginformation: scheduling information of the DMRS, scheduling informationof the first PTRS, scheduling information of a sounding reference signal(SRS), and scheduling information of a codeword.

It should be understood that the transmission apparatus 1000 herein isembodied in the form of functional units. The term “unit” herein may bean ASIC, an electronic circuit, a processor (for example, a sharedprocessor, a dedicated processor, or a group processor) for executingone or more software or firmware programs, a memory, a combinationallogic circuit, and/or another appropriate component supporting thedescribed functions. In an optional example, a person skilled in the artmay understand that the transmission apparatus 1000 may be specificallythe terminal device in the embodiment of the transmission method 500,and the transmission apparatus 1000 may be configured to performprocedures and/or steps that are corresponding to the terminal device inthe embodiment of the transmission method 500. To avoid repetition,details are not described herein again.

FIG. 11 shows a reference signal transmission apparatus 1100 accordingto an embodiment of this application. The transmission apparatus 1100may be a network device in the communications system shown in FIG. 1. Ahardware architecture shown in FIG. 11 may be used for the networkdevice. The network device may include a processor 1110, a transceiver1120, and a memory 1130, and the processor 1110, the transceiver 1120,and the memory 1130 communicate with each other by using an internalconnection path. Related functions implemented by the processing unit710 in FIG. 7 may be implemented by the processor 1110, and relatedfunctions implemented by the transceiver unit 720 may be implemented bythe transceiver 1120.

The processor 1110 may include one or more processors, for example, oneor more central processing units (CPU). When the processor is one CPU,the CPU may be a single-core CPU, or may be a multi-core CPU.

The transceiver 1120 is configured to send data and/or a signal, andreceive data and/or a signal. The transceiver may include a transmitterand a receiver. The transmitter is configured to send data and/or asignal, and the receiver is configured to receive data and/or a signal.

The memory 1130 includes but is not limited to a random access memory(RAM), a read-only memory (ROM), an erasable programmable read onlymemory (EPROM), and a compact disc read-only memory (CD-ROM), and thememory 1130 is configured to store a related instruction and relateddata.

The memory 1130 is configured to store program code and data of thenetwork device, and may be a separate component or integrated into theprocessor 1110.

Specifically, the processor 1110 is configured to control thetransceiver to perform transmission of a reference signal with aterminal device, for example, perform a part of S330. For details, referto the descriptions in the method embodiment, and details are notdescribed herein again.

It may be understood that FIG. 11 merely shows a simplified design ofthe network device. In an actual application, the network device mayfurther separately include other necessary elements, including but notlimited to any quantity of transceivers, processors, controllers,memories, and the like, and all network devices that can implement thisapplication fall within the protection scope of this application.

In a possible design, the transmission apparatus 1100 may be a chip, forexample, may be a communications chip that may be used in a networkdevice, and is configured to implement a related function of theprocessor 1110 in the network device. The chip may be a fieldprogrammable gate array, a dedicated integrated chip, a system chip, acentral processing unit, a network processor, a digital signalprocessing circuit, or a microcontroller for implementing a relatedfunction, or may be a programmable controller or another integratedchip. Optionally, the chip may include one or more memories, configuredto store program code, and when executing the code, a processorimplements a corresponding function.

FIG. 12 shows a reference signal transmission apparatus 1200 accordingto an embodiment of this application. The transmission apparatus 1200may be a terminal device in the communications system shown in FIG. 1. Ahardware architecture shown in FIG. 12 may be used for the terminaldevice. The terminal device may include a processor 1210, a transceiver1220, and a memory 1230, and the processor 1210, the transceiver 1220,and the memory 1230 communicate with each other by using an internalconnection path. Related functions implemented by the processing unit810 in FIG. 8 may be implemented by the processor 1210, and relatedfunctions implemented by the transceiver unit 820 may be implemented bythe transceiver 1220.

The processor 1210 may include one or more processors, for example, oneor more central processing units CPUs. When the processor is one CPU,the CPU may be a single-core CPU, or may be a multi-core CPU.

The transceiver 1220 is configured to send data and/or a signal, andreceive data and/or a signal. The transceiver may include a transmitterand a receiver. The transmitter is configured to send data and/or asignal, and the receiver is configured to receive data and/or a signal.

The memory 1230 includes but is not limited to a RAM, a ROM, an EPROM,or a CD-ROM, and the memory 1230 is configured to store a relatedinstruction and related data.

The memory 1230 is configured to store program code and data of theterminal device, and may be a separate component or integrated into theprocessor 1210.

Specifically, the processor 1210 is configured to control thetransceiver to perform transmission of a reference signal with a networkdevice, for example, perform a part of S330. For details, refer to thedescriptions in the method embodiment, and details are not describedherein again.

It may be understood that FIG. 12 merely shows a simplified design ofthe terminal device. In an actual application, the terminal device mayfurther separately include other necessary elements, including but notlimited to any quantity of transceivers, processors, controllers,memories, and the like, and all terminal devices that can implement thisapplication fall within the protection scope of this application.

In a possible design, the transmission apparatus 1200 may be a chip, forexample, may be a communications chip that may be used in a terminaldevice, and is configured to implement a related function of theprocessor 1210 in the terminal device. The chip may be a fieldprogrammable gate array, a dedicated integrated chip, a system chip, acentral processing unit, a network processor, a digital signalprocessing circuit, or a microcontroller for implementing a relatedfunction, or may be a programmable controller or another integratedchip. Optionally, the chip may include one or more memories, configuredto store program code, and when executing the code, a processorimplements a corresponding function.

FIG. 13 shows a reference signal transmission apparatus 1300 accordingto an embodiment of this application. The transmission apparatus 1300may be a network device in the communications system shown in FIG. 1. Ahardware architecture shown in FIG. 13 may be used for the networkdevice. The network device may include a processor 1310, a transceiver1320, and a memory 1330, and the processor 1310, the transceiver 1320,and the memory 1330 communicate with each other by using an internalconnection path. Related functions implemented by the processing unit910 in FIG. 9 may be implemented by the processor 1310, and relatedfunctions implemented by the transceiver unit 920 may be implemented bythe transceiver 1320.

The processor 1310 may include one or more processors, for example, oneor more central processing units (CPU). When the processor is one CPU,the CPU may be a single-core CPU, or may be a multi-core CPU.

The transceiver 1320 is configured to send data and/or a signal, andreceive data and/or a signal. The transceiver may include a transmitterand a receiver. The transmitter is configured to send data and/or asignal, and the receiver is configured to receive data and/or a signal.

The memory 1330 includes but is not limited to a RAM, a ROM, an EPROM,or a CD-ROM, and the memory 1330 is configured to store a relatedinstruction and related data.

The memory 1330 is configured to store program code and data of thenetwork device, and may be a separate component or integrated into theprocessor 1310.

Specifically, the processor 1310 is configured to control thetransceiver to perform transmission of a reference signal with aterminal device, for example, perform a part of S330. For details, referto the descriptions in the method embodiment, and details are notdescribed herein again.

It may be understood that FIG. 13 merely shows a simplified design ofthe network device. In an actual application, the network device mayfurther separately include other necessary elements, including but notlimited to any quantity of transceivers, processors, controllers,memories, and the like, and all network devices that can implement thisapplication fall within the protection scope of this application.

In a possible design, the transmission apparatus 1300 may be a chip, forexample, may be a communications chip that may be used in a networkdevice, and is configured to implement a related function of theprocessor 1310 in the network device. The chip may be a fieldprogrammable gate array, a dedicated integrated chip, a system chip, acentral processing unit, a network processor, a digital signalprocessing circuit, or a microcontroller for implementing a relatedfunction, or may be a programmable controller or another integratedchip. Optionally, the chip may include one or more memories, configuredto store program code, and when executing the code, a processorimplements a corresponding function.

FIG. 14 shows a reference signal transmission apparatus 1400 accordingto an embodiment of this application. The transmission apparatus 1400may be a terminal device in the communications system shown in FIG. 1. Ahardware architecture shown in FIG. 14 may be used for the terminaldevice. The terminal device may include a processor 1410, a transceiver1420, and a memory 1430, and the processor 1410, the transceiver 1420,and the memory 1430 communicate with each other by using an internalconnection path. Related functions implemented by the processing unit1010 in FIG. 10 may be implemented by the processor 1410, and relatedfunctions implemented by the transceiver unit 1020 may be implemented bythe transceiver 1420.

The processor 1410 may include one or more processors, for example, oneor more central processing units CPUs. When the processor is one CPU,the CPU may be a single-core CPU, or may be a multi-core CPU.

The transceiver 1420 is configured to send data and/or a signal, andreceive data and/or a signal. The transceiver may include a transmitterand a receiver. The transmitter is configured to send data and/or asignal, and the receiver is configured to receive data and/or a signal.

The memory 1430 includes but is not limited to a RAM, a ROM, an EPROM,or a CD-ROM, and the memory 1430 is configured to store a relatedinstruction and related data.

The memory 1430 is configured to store program code and data of theterminal device, and may be a separate component or integrated into theprocessor 1410.

Specifically, the processor 1410 is configured to control thetransceiver to perform transmission of a reference signal with a networkdevice, for example, perform a part of S330. For details, refer to thedescriptions in the method embodiment, and details are not describedherein again.

It may be understood that FIG. 14 merely shows a simplified design ofthe terminal device. In an actual application, the terminal device mayfurther separately include other necessary elements, including but notlimited to any quantity of transceivers, processors, controllers,memories, and the like, and all terminal devices that can implement thisapplication fall within the protection scope of this application.

In a possible design, the transmission apparatus 1400 may be a chip, forexample, may be a communications chip that may be used in a terminaldevice, and is configured to implement a related function of theprocessor 1410 in the terminal device. The chip may be a fieldprogrammable gate array, a dedicated integrated chip, a system chip, acentral processing unit, a network processor, a digital signalprocessing circuit, or a microcontroller for implementing a relatedfunction, or may be a programmable controller or another integratedchip. Optionally, the chip may include one or more memories, configuredto store program code, and when executing the code, a processorimplements a corresponding function.

All or some of the foregoing embodiments may be implemented by usingsoftware, hardware, firmware, or any combination thereof. When softwareis used to implement the embodiments, all or some of the embodiments maybe implemented in a form of a computer program product. The computerprogram product includes one or more computer instructions. When thecomputer program instructions are loaded and executed on a computer, theprocedures or functions in the embodiments of this application are allor partially generated. The computer may be a general-purpose computer,a special-purpose computer, a computer network, or another programmableapparatus. The computer instructions may be stored in a computerreadable storage medium or may be transmitted by using the computerreadable storage medium. The computer instructions may be transmittedfrom a website, computer, server, or data center to another web site,computer, server, or data center in a wired (for example, a coaxialcable, an optical fiber, or a digital subscriber line (DSL)) or wireless(for example, infrared, radio, or microwave) manner. The computerreadable storage medium may be any usable medium accessible by acomputer, or a data storage device, such as a server or a data center,integrating one or more usable media. The usable medium may be amagnetic medium (for example, a floppy disk, a hard disk, or a magnetictape), an optical medium (for example, a digital versatile disc (DVD)),a semiconductor medium (for example, a solid state disk (SSD)), or thelike.

A person of ordinary skill in the art may understand that all or some ofthe processes of the methods in the embodiments may be implemented by acomputer program instructing relevant hardware. The program may bestored in a computer readable storage medium. When the program runs, theprocesses of the method embodiments may be performed. The storage mediumincludes any medium that can store program code, such as a ROM, a RAM, amagnetic disk, or an optical disc.

A person of ordinary skill in the art may be aware that, the units andalgorithm steps in the examples described with reference to theembodiments disclosed in this specification can be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of this application.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the system, apparatus, and unit, refer to a correspondingprocess in the method embodiments. Details are not described hereinagain.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented by using some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electrical, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualneeds to achieve the objectives of the solutions of the embodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units may be integrated into one unit.

When the functions are implemented in a form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer readable storage medium. Based on such anunderstanding, the technical solutions of this application essentially,or the part contributing to the prior art, or some of the technicalsolutions may be implemented in a form of a software product. Thecomputer software product is stored in a storage medium, and includesseveral instructions for instructing a computer device (which may be apersonal computer, a server, a network device, or the like) to performall or some of the steps of the methods described in the embodiments ofthis application. The storage medium includes any medium that can storeprogram code, such as a USB flash drive, a removable hard disk, a ROM, aRAM, a magnetic disk, or an optical disc.

The foregoing descriptions are merely specific implementations of thisapplication, but are not intended to limit the protection scope of thisapplication. Any variation or replacement readily figured out by aperson skilled in the art within the technical scope disclosed in thisapplication shall fall within the protection scope of this application.Therefore, the protection scope of this application shall be subject tothe protection scope of the claims.

What is claimed is:
 1. A reference signal communication method,comprising: determining a resource block offset of a frequency domainposition of a phase tracking reference signal (PTRS) based on afrequency domain density of the PTRS, an identifier of a terminaldevice, and a first bandwidth, in accordance with a ratio of the firstbandwidth to the frequency domain density of the PTRS being anon-integer; wherein the first bandwidth is a bandwidth scheduled by anetwork device for the terminal device; and sending or receiving thePTRS based on the resource block offset of the frequency domain positionof the PTRS.
 2. The communication method according to claim 1, whereinthe resource block offset of the frequency domain position of the PTRS,the frequency domain density of the PTRS, the first bandwidth and theidentifier of the terminal device meet following relation:Δf=ID_(UE) mod(BW₁ mod FD_(step)), where: FD_(step) is the frequencydomain density of the PTRS, BW₁ is the first bandwidth, ID_(UE) is theidentifier of the terminal device, and Δf is the resource block offsetof the frequency domain position of the PTRS.
 3. The communicationmethod according to claim 1, further comprising: determining theresource block offset of the frequency domain position of the PTRS basedon the frequency domain density of the PTRS and the identifier of theterminal device in accordance with the ratio of the first bandwidth tothe frequency domain density of the PTRS being an integer; wherein theresource block offset of the frequency domain position of the PTRS, thefrequency domain density of the PTRS, and the identifier of the terminaldevice meet following relation:Δf=ID_(UE) mod FD_(step), where: FD_(step) is the frequency domaindensity of the PTRS, ID_(UE) is the identifier of the terminal device,and Δf is the resource block offset of the frequency domain position ofthe PTRS.
 4. The communication method according to claim 1, wherein avalue of the frequency domain density of the PTRS is 2 or
 4. 5. Thecommunication method according to claim 1, further comprising:determining the frequency domain density of the PTRS according to: thefirst bandwidth, and a mapping relationship between PTRS frequencydomain densities and scheduled bandwidths.
 6. A communication apparatus,comprising: a processor, configured to determine a resource block offsetof a frequency domain position of a phase tracking reference signal(PTRS) based on a frequency domain density of the PTRS, an identifier ofa terminal device, and a first bandwidth, in accordance with a ratio ofthe first bandwidth to the frequency domain density of the PTRS being anon-integer; wherein the first bandwidth is a bandwidth scheduled by anetwork device for the terminal device; and a transceiver, configured tosending or receiving the PTRS based on the resource block offset of thefrequency domain position of the PTRS.
 7. The communication apparatusaccording to claim 6, wherein the resource block offset of the frequencydomain position of the PTRS, the frequency domain density of the PTRS,the first bandwidth and the identifier of the terminal device meetfollowing relation:Δf=ID_(UE) mod(BW₁ mod FD_(step)), where: FD_(step) is the frequencydomain density of the PTRS, BW₁ is the first bandwidth, ID_(UE) is theidentifier of the terminal device, and Δf is the resource block offsetof the frequency domain position of the PTRS.
 8. The communicationapparatus according to claim 6, wherein: the processor is furtherconfigured to: determine the resource block offset of the frequencydomain position of the PTRS based on the frequency domain density of thePTRS and the identifier of the terminal device in accordance with theratio of the first bandwidth to the frequency domain density of the PTRSbeing an integer; wherein the resource block offset of the frequencydomain position of the PTRS, the frequency domain density of the PTRS,and the identifier of the terminal device meet following relation:Δf=ID_(UE) mod FD_(step), where: FD_(step) is the frequency domaindensity of the PTRS, ID_(UE) is the identifier of the terminal device,and Δf is the resource block offset of the frequency domain position ofthe PTRS.
 9. The communication apparatus according to claim 6, wherein avalue of the frequency domain density of the PTRS is 2 or
 4. 10. Thecommunication apparatus according to claim 6, wherein: the processor isfurther configured to determine the frequency domain density of the PTRSaccording to: the first bandwidth, and a mapping relationship betweenPTRS frequency domain densities and scheduled bandwidths.
 11. Anon-transitory computer readable storage medium, wherein a computerprogram is stored in the computer readable storage medium, and when theprogram is executed, a communication method is implemented, comprising:determining a resource block offset of a frequency domain position of aphase tracking reference signal (PTRS) based on a frequency domaindensity of the PTRS, an identifier of a terminal device, and a firstbandwidth, in accordance with a ratio of the first bandwidth to thefrequency domain density of the PTRS being a non-integer; wherein thefirst bandwidth is a bandwidth scheduled by a network device for theterminal device; and sending or receiving the PTRS based on the resourceblock offset of the frequency domain position of the PTRS.
 12. Thenon-transitory computer readable storage medium according to claim 11,wherein the resource block offset of the frequency domain position ofthe PTRS, the frequency domain density of the PTRS, the first bandwidthand the identifier of the terminal device meet following relation:Δf=ID_(UE) mod(BW₁ mod FD_(step)), where: FD_(step) is the frequencydomain density of the PTRS, BW₁ is the first bandwidth, ID_(UE) is theidentifier of the terminal device, and Δf is the resource block offsetof the frequency domain position of the PTRS.
 13. The non-transitorycomputer readable storage medium according to claim 11, furthercomprising: determining the resource block offset of the frequencydomain position of the PTRS based on the frequency domain density of thePTRS and the identifier of the terminal device in accordance with theratio of the first bandwidth to the frequency domain density of the PTRSbeing an integer; wherein the resource block offset of the frequencydomain position of the PTRS, the frequency domain density of the PTRS,and the identifier of the terminal device meet following relation:Δf=ID_(UE) mod FD_(step), where: FD_(step) is the frequency domaindensity of the PTRS, ID_(UE) is the identifier of the terminal device,and Δf is the resource block offset of the frequency domain position ofthe PTRS.
 14. The non-transitory computer readable storage mediumaccording to claim 11, wherein a value of the frequency domain densityof the PTRS is 2 or
 4. 15. The non-transitory computer readable storagemedium according to claim 11, further comprising: determining thefrequency domain density of the PTRS according to: the first bandwidth,and a mapping relationship between PTRS frequency domain densities andscheduled bandwidths.
 16. A communication apparatus, comprising: aprocessor, configured to execute computer program of a memory to carryout a communications method comprising: determining a resource blockoffset of a frequency domain position of a phase tracking referencesignal (PTRS) based on a frequency domain density of the PTRS, anidentifier of a terminal device, and a first bandwidth, in accordancewith a ratio of the first bandwidth to the frequency domain density ofthe PTRS being a non-integer; wherein the first bandwidth is a bandwidthscheduled by a network device for the terminal device; and sending orreceiving the PTRS based on the resource block offset of the frequencydomain position of the PTRS.
 17. A communications apparatus, wherein thecommunications apparatus comprises a processor, a memory, and aninstruction that is stored on the memory and run on the processor, andwhen the instruction is run, the communications apparatus performs themethod according to claim
 1. 18. The communication apparatus accordingto claim 16, wherein the resource block offset of the frequency domainposition of the PTRS, the frequency domain density of the PTRS, thefirst bandwidth and the identifier of the terminal device meet followingrelation:Δf=ID_(UE) mod(BW₁ mod FD_(step)), where: FD_(step) is the frequencydomain density of the PTRS, BW₁ is the first bandwidth, ID_(UE) is theidentifier of the terminal device, and Δf is the resource block offsetof the frequency domain position of the PTRS.
 19. The communicationapparatus according to claim 16, wherein the communications methodfurther comprises: determining the resource block offset of thefrequency domain position of the PTRS based on the frequency domaindensity of the PTRS and the identifier of the terminal device inaccordance with the ratio of the first bandwidth to the frequency domaindensity of the PTRS being an integer; wherein the resource block offsetof the frequency domain position of the PTRS, the frequency domaindensity of the PTRS, and the identifier of the terminal device meetfollowing relation:Δf=ID_(UE) mod FD_(step), where: FD_(step) is the frequency domaindensity of the PTRS, ID_(UE) is the identifier of the terminal device,and Δf is the resource block offset of the frequency domain position ofthe PTRS.
 20. The communication apparatus according to claim 16, whereina value of the frequency domain density of the PTRS is 2 or
 4. 21. Thecommunication apparatus according to claim 16, wherein thecommunications method further comprises: determining the frequencydomain density of the PTRS according to: the first bandwidth, and amapping relationship between PTRS frequency domain densities andscheduled bandwidths.